diff --git a/.gitignore b/.gitignore
index 1994952e..c19d22ba 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,7 +1,7 @@
 .gradle
 build
 
-.settings
+**/.settings
 .classpath
 .project
 
@@ -9,3 +9,4 @@ build
 *.iml
 
 /plugin-integration/gradle-ssh-plugin
+/bin/
diff --git a/build.gradle b/build.gradle
index 7866ad1d..d5b096ce 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,22 +1,27 @@
 allprojects {
-    group = 'org.hidetake'
-    version = System.getenv('CIRCLE_TAG') ?: 'SNAPSHOT'
+	group = 'org.hidetake'
+	version = System.getenv('CIRCLE_TAG') ?: 'SNAPSHOT'
 
-    repositories {
-        jcenter()
-    }
+	afterEvaluate {
+		tasks.withType(Test) {
+			finalizedBy ':testReport'
+			testReport.reportOn binaryResultsDirectory
+			reports.html.required = false
+			reports.junitXml.destination = file("${rootProject.buildDir}/test-results")
+		}
+	}
 
-    afterEvaluate {
-        tasks.withType(Test) {
-            finalizedBy ':testReport'
-            testReport.reportOn binResultsDir
-            reports.html.enabled = false
-            reports.junitXml.destination = file("${rootProject.buildDir}/test-results")
-        }
-    }
+	plugins.withType(JavaPlugin) {
+		dependencies {
+			implementation 'com.github.mwiede:jsch:0.2.5'
+			implementation 'org.slf4j:slf4j-api:2.0.6'
+			implementation 'junit:junit:4.11'
+			implementation 'org.spockframework:spock-core:2.3-groovy-3.0'
+		}
+	}
 }
 
 task testReport(type: TestReport) {
-    description 'Generates test report for all projects'
-    destinationDir = file("$buildDir/reports")
+	description 'Generates test report for all projects'
+	destinationDirectory = file("$buildDir/reports")
 }
diff --git a/cli/build.gradle b/cli/build.gradle
deleted file mode 100644
index d00ef67d..00000000
--- a/cli/build.gradle
+++ /dev/null
@@ -1,48 +0,0 @@
-plugins {
-    id 'groovy'
-    id 'application'
-    id 'com.github.johnrengelman.shadow' version '5.0.0'
-}
-
-java {
-    sourceCompatibility = JavaVersion.VERSION_1_8
-    targetCompatibility = JavaVersion.VERSION_1_8
-}
-
-mainClassName = 'org.hidetake.groovy.ssh.Main'
-
-dependencies {
-    compile project(':core')
-    compile 'ch.qos.logback:logback-classic:1.1.2'
-
-    runtime 'commons-cli:commons-cli:1.2'
-
-    testCompile project(':server-integration-test')
-
-    testCompile 'org.codehaus.groovy.modules.http-builder:http-builder:0.7.1'
-
-    testCompile 'org.spockframework:spock-core:1.2-groovy-2.5'
-    testRuntime 'cglib:cglib-nodep:3.2.10'
-    testRuntime 'org.objenesis:objenesis:3.0.1'
-}
-
-test {
-    mustRunAfter ':server-integration-test:check'
-
-    if (System.getProperty('os.name') == 'Linux') {
-        systemProperty 'java.security.egd', 'file:/dev/./urandom'
-    }
-}
-
-shadowJar {
-    baseName = 'gssh'
-    classifier = ''
-    version = ''
-}
-
-runShadow {
-    args "$projectDir/gssh-example.groovy"
-    workingDir rootDir
-}
-
-check.dependsOn runShadow
diff --git a/core/bin/.gitignore b/core/bin/.gitignore
new file mode 100644
index 00000000..7eed456b
--- /dev/null
+++ b/core/bin/.gitignore
@@ -0,0 +1,2 @@
+/main/
+/test/
diff --git a/core/build.gradle b/core/build.gradle
index cb8bcf81..59ba2c77 100644
--- a/core/build.gradle
+++ b/core/build.gradle
@@ -1,28 +1,17 @@
 plugins {
     id 'groovy'
     id 'maven-publish'
-    id 'com.jfrog.bintray' version '1.8.4'
 }
 
-java {
-    sourceCompatibility = JavaVersion.VERSION_1_8
-    targetCompatibility = JavaVersion.VERSION_1_8
+repositories {
+    mavenCentral()
 }
 
 dependencies {
-    compile 'org.codehaus.groovy:groovy-all:2.5.6'
-    compile 'org.slf4j:slf4j-api:1.7.7'
-    compile 'com.jcraft:jsch:0.1.55'
-    compile 'com.jcraft:jsch.agentproxy.connector-factory:0.0.9'
-    compile 'com.jcraft:jsch.agentproxy.jsch:0.0.9'
+    testRuntimeOnly 'cglib:cglib-nodep:3.2.10'
+    testRuntimeOnly 'org.objenesis:objenesis:3.0.1'
 
-    testCompile('org.spockframework:spock-core:1.2-groovy-2.5') {
-        exclude group: 'org.codehaus.groovy', module:'groovy-all'
-    }
-    testRuntime 'cglib:cglib-nodep:3.2.10'
-    testRuntime 'org.objenesis:objenesis:3.0.1'
-
-    testRuntime 'ch.qos.logback:logback-classic:1.1.2'
+    testRuntimeOnly 'ch.qos.logback:logback-classic:1.1.2'
 }
 
 processResources {
@@ -84,20 +73,4 @@ publishing {
             }
         }
     }
-}
-
-bintray {
-    user = System.getenv('BINTRAY_USER') ?: findProperty('bintrayUser')
-    key  = System.getenv('BINTRAY_KEY')  ?: findProperty('bintrayKey')
-    publications = ['release']
-    publish = true
-    pkg {
-        repo = 'maven'
-        name = parent.name
-        licenses = [project.license]
-        vcsUrl = project.vcsUrl
-        version {
-            name = project.version
-        }
-    }
-}
+}
\ No newline at end of file
diff --git a/core/src/main/groovy/org/hidetake/groovy/ssh/connection/HostAuthentication.groovy b/core/src/main/groovy/org/hidetake/groovy/ssh/connection/HostAuthentication.groovy
index 4b37a544..bc2ed542 100644
--- a/core/src/main/groovy/org/hidetake/groovy/ssh/connection/HostAuthentication.groovy
+++ b/core/src/main/groovy/org/hidetake/groovy/ssh/connection/HostAuthentication.groovy
@@ -58,7 +58,7 @@ trait HostAuthentication {
     }
 
     @Slf4j
-    private static class Helper {
+    static class Helper {
         final Session session
         final Remote remote
 
diff --git a/core/src/main/groovy/org/hidetake/groovy/ssh/connection/ProxyValidator.groovy b/core/src/main/groovy/org/hidetake/groovy/ssh/connection/ProxyValidator.groovy
index 6d976aae..31058c7e 100644
--- a/core/src/main/groovy/org/hidetake/groovy/ssh/connection/ProxyValidator.groovy
+++ b/core/src/main/groovy/org/hidetake/groovy/ssh/connection/ProxyValidator.groovy
@@ -3,8 +3,6 @@ package org.hidetake.groovy.ssh.connection
 import org.hidetake.groovy.ssh.core.Proxy
 import org.hidetake.groovy.ssh.core.ProxyType
 
-import static ProxyType.SOCKS
-
 /**
  * Basic validation and defaults for proxied connections created by {@link ConnectionManager}.
  *  
diff --git a/core/src/main/groovy/org/hidetake/groovy/ssh/connection/UserAuthentication.groovy b/core/src/main/groovy/org/hidetake/groovy/ssh/connection/UserAuthentication.groovy
index 7a9d7aec..594650ea 100644
--- a/core/src/main/groovy/org/hidetake/groovy/ssh/connection/UserAuthentication.groovy
+++ b/core/src/main/groovy/org/hidetake/groovy/ssh/connection/UserAuthentication.groovy
@@ -1,11 +1,14 @@
 package org.hidetake.groovy.ssh.connection
 
+import org.hidetake.groovy.ssh.core.Remote
+
+import com.jcraft.jsch.AgentIdentityRepository
+import com.jcraft.jsch.IdentityRepository
 import com.jcraft.jsch.JSch
+import com.jcraft.jsch.SSHAgentConnector
 import com.jcraft.jsch.Session
-import com.jcraft.jsch.agentproxy.ConnectorFactory
-import com.jcraft.jsch.agentproxy.RemoteIdentityRepository
+
 import groovy.util.logging.Slf4j
-import org.hidetake.groovy.ssh.core.Remote
 
 @Slf4j
 trait UserAuthentication {
@@ -25,7 +28,9 @@ trait UserAuthentication {
         }
 
         if (settings.agent) {
-            jsch.identityRepository = RemoteIdentityRepositoryLocator.get()
+			// Use agent authentication using https://github.com/mwiede/jsch/issues/65#issuecomment-913051572
+			IdentityRepository irepo = new AgentIdentityRepository(new SSHAgentConnector())
+            jsch.identityRepository = irepo
             log.debug("Using SSH agent authentication for $remote")
         } else {
             jsch.identityRepository = null    /* null means the default repository */
@@ -42,17 +47,4 @@ trait UserAuthentication {
             }
         }
     }
-
-    private static class RemoteIdentityRepositoryLocator {
-        private static instance = null
-
-        static get() {
-            if (instance) {
-                instance
-            } else {
-                instance = new RemoteIdentityRepository(ConnectorFactory.default.createConnector())
-            }
-        }
-    }
-
-}
+}
\ No newline at end of file
diff --git a/core/src/main/groovy/org/hidetake/groovy/ssh/core/container/Container.groovy b/core/src/main/groovy/org/hidetake/groovy/ssh/core/container/Container.groovy
index c75064ce..813b762b 100644
--- a/core/src/main/groovy/org/hidetake/groovy/ssh/core/container/Container.groovy
+++ b/core/src/main/groovy/org/hidetake/groovy/ssh/core/container/Container.groovy
@@ -43,7 +43,7 @@ trait Container<T> implements Map<String, T> {
      * @param closure
      * @return item
      */
-    T create(String name, @DelegatesTo(T) Closure closure) {
+    T create(String name, Closure closure) {
         assert name
         assert getContainerElementType() instanceof Class<T>
         T namedObject = getContainerElementType().newInstance(name)
diff --git a/core/src/main/groovy/org/hidetake/groovy/ssh/session/SessionExtensions.groovy b/core/src/main/groovy/org/hidetake/groovy/ssh/session/SessionExtensions.groovy
index 97444d04..75bc4a54 100644
--- a/core/src/main/groovy/org/hidetake/groovy/ssh/session/SessionExtensions.groovy
+++ b/core/src/main/groovy/org/hidetake/groovy/ssh/session/SessionExtensions.groovy
@@ -6,19 +6,15 @@ import org.hidetake.groovy.ssh.session.transfer.FileGet
 import org.hidetake.groovy.ssh.session.transfer.FilePut
 import org.hidetake.groovy.ssh.session.transfer.SftpRemove
 
+import groovy.util.logging.Slf4j
+
 /**
  * A set of extensions to be shipped as default.
  *
  * @author Hidetake Iwata
  */
-trait SessionExtensions implements
-        Command,
-        BackgroundCommand,
-        Script,
-        Shell,
-        Sudo,
-        FileGet,
-        FilePut,
-        SftpRemove,
-        PortForward {
-}
+@Slf4j
+trait SessionExtensions implements Command, BackgroundCommand, Script, 
+ Shell, Sudo, FileGet, FilePut, SftpRemove, PortForward {
+	 
+ }
\ No newline at end of file
diff --git a/core/src/main/groovy/org/hidetake/groovy/ssh/session/SessionHandler.groovy b/core/src/main/groovy/org/hidetake/groovy/ssh/session/SessionHandler.groovy
index 7df65f5f..98cfad3b 100644
--- a/core/src/main/groovy/org/hidetake/groovy/ssh/session/SessionHandler.groovy
+++ b/core/src/main/groovy/org/hidetake/groovy/ssh/session/SessionHandler.groovy
@@ -1,6 +1,5 @@
 package org.hidetake.groovy.ssh.session
 
-import groovy.util.logging.Slf4j
 import org.hidetake.groovy.ssh.core.Remote
 import org.hidetake.groovy.ssh.core.settings.CompositeSettings
 import org.hidetake.groovy.ssh.core.settings.GlobalSettings
@@ -8,6 +7,8 @@ import org.hidetake.groovy.ssh.core.settings.PerServiceSettings
 import org.hidetake.groovy.ssh.operation.Operations
 import org.hidetake.groovy.ssh.operation.SftpOperations
 
+import groovy.util.logging.Slf4j
+
 /**
  * A handler of {@link org.hidetake.groovy.ssh.core.RunHandler#session(Remote, groovy.lang.Closure)}.
  *
diff --git a/core/src/main/groovy/org/hidetake/groovy/ssh/session/execution/Command.groovy b/core/src/main/groovy/org/hidetake/groovy/ssh/session/execution/Command.groovy
index d511233d..a424d96e 100644
--- a/core/src/main/groovy/org/hidetake/groovy/ssh/session/execution/Command.groovy
+++ b/core/src/main/groovy/org/hidetake/groovy/ssh/session/execution/Command.groovy
@@ -6,12 +6,15 @@ import org.hidetake.groovy.ssh.operation.Operations
 import org.hidetake.groovy.ssh.session.BadExitStatusException
 import org.hidetake.groovy.ssh.session.SessionExtension
 
+import groovy.util.logging.Slf4j
+
 /**
  * Provides the blocking command execution.
  * Each method blocks until channel is closed.
  *
  * @author Hidetake Iwata
  */
+@Slf4j
 trait Command implements SessionExtension {
     void execute(HashMap map = [:], String commandLine, Closure callback) {
         assert callback, 'callback must be given'
@@ -36,7 +39,7 @@ trait Command implements SessionExtension {
         execute(map, Escape.escape(commandLineArgs))
     }
 
-    private static class Helper {
+    static class Helper {
         static execute(Operations operations, CommandSettings settings, String commandLine) {
             def operation = operations.command(settings, commandLine)
 
diff --git a/core/src/main/groovy/org/hidetake/groovy/ssh/session/execution/Script.groovy b/core/src/main/groovy/org/hidetake/groovy/ssh/session/execution/Script.groovy
index 46bcd391..2f86ba59 100644
--- a/core/src/main/groovy/org/hidetake/groovy/ssh/session/execution/Script.groovy
+++ b/core/src/main/groovy/org/hidetake/groovy/ssh/session/execution/Script.groovy
@@ -30,7 +30,7 @@ trait Script implements Command {
         execute(Helper.createSettings(settings, script), Helper.guessInterpreter(script), callback)
     }
 
-    private static class Helper {
+    static class Helper {
         static HashMap createSettings(HashMap settings, def script) {
             if (settings.inputStream) {
                 throw new IllegalArgumentException("executeScript does not work with inputStream: $settings")
diff --git a/docs/build.gradle b/docs/build.gradle
index 7dc26cbc..997ec14f 100644
--- a/docs/build.gradle
+++ b/docs/build.gradle
@@ -1,5 +1,5 @@
 plugins {
-    id 'org.asciidoctor.convert' version '1.5.3'
+    id 'org.asciidoctor.jvm.convert' version '2.4.0'
 }
 
 asciidoctor {
@@ -7,4 +7,4 @@ asciidoctor {
         include 'index.adoc'
         include 'example-script.adoc'
     }
-}
+}
\ No newline at end of file
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index 87b738cb..249e5832 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 44e7c4d1..070cb702 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-5.2.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.6-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
index af6708ff..a69d9cb6 100755
--- a/gradlew
+++ b/gradlew
@@ -1,78 +1,129 @@
-#!/usr/bin/env sh
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
 
 ##############################################################################
-##
-##  Gradle start up script for UN*X
-##
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
 ##############################################################################
 
 # Attempt to set APP_HOME
+
 # Resolve links: $0 may be a link
-PRG="$0"
-# Need this for relative symlinks.
-while [ -h "$PRG" ] ; do
-    ls=`ls -ld "$PRG"`
-    link=`expr "$ls" : '.*-> \(.*\)$'`
-    if expr "$link" : '/.*' > /dev/null; then
-        PRG="$link"
-    else
-        PRG=`dirname "$PRG"`"/$link"
-    fi
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
 done
-SAVED="`pwd`"
-cd "`dirname \"$PRG\"`/" >/dev/null
-APP_HOME="`pwd -P`"
-cd "$SAVED" >/dev/null
+
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
 
 APP_NAME="Gradle"
-APP_BASE_NAME=`basename "$0"`
+APP_BASE_NAME=${0##*/}
 
 # Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS='"-Xmx64m"'
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
-MAX_FD="maximum"
+MAX_FD=maximum
 
 warn () {
     echo "$*"
-}
+} >&2
 
 die () {
     echo
     echo "$*"
     echo
     exit 1
-}
+} >&2
 
 # OS specific support (must be 'true' or 'false').
 cygwin=false
 msys=false
 darwin=false
 nonstop=false
-case "`uname`" in
-  CYGWIN* )
-    cygwin=true
-    ;;
-  Darwin* )
-    darwin=true
-    ;;
-  MINGW* )
-    msys=true
-    ;;
-  NONSTOP* )
-    nonstop=true
-    ;;
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
 esac
 
 CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
 
+
 # Determine the Java command to use to start the JVM.
 if [ -n "$JAVA_HOME" ] ; then
     if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
         # IBM's JDK on AIX uses strange locations for the executables
-        JAVACMD="$JAVA_HOME/jre/sh/java"
+        JAVACMD=$JAVA_HOME/jre/sh/java
     else
-        JAVACMD="$JAVA_HOME/bin/java"
+        JAVACMD=$JAVA_HOME/bin/java
     fi
     if [ ! -x "$JAVACMD" ] ; then
         die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
@@ -81,7 +132,7 @@ Please set the JAVA_HOME variable in your environment to match the
 location of your Java installation."
     fi
 else
-    JAVACMD="java"
+    JAVACMD=java
     which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
 
 Please set the JAVA_HOME variable in your environment to match the
@@ -89,84 +140,101 @@ location of your Java installation."
 fi
 
 # Increase the maximum file descriptors if we can.
-if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
-    MAX_FD_LIMIT=`ulimit -H -n`
-    if [ $? -eq 0 ] ; then
-        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
-            MAX_FD="$MAX_FD_LIMIT"
-        fi
-        ulimit -n $MAX_FD
-        if [ $? -ne 0 ] ; then
-            warn "Could not set maximum file descriptor limit: $MAX_FD"
-        fi
-    else
-        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
-    fi
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
 fi
 
-# For Darwin, add options to specify how the application appears in the dock
-if $darwin; then
-    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
-fi
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
 
-# For Cygwin, switch paths to Windows format before running java
-if $cygwin ; then
-    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
-    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
-    JAVACMD=`cygpath --unix "$JAVACMD"`
-
-    # We build the pattern for arguments to be converted via cygpath
-    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
-    SEP=""
-    for dir in $ROOTDIRSRAW ; do
-        ROOTDIRS="$ROOTDIRS$SEP$dir"
-        SEP="|"
-    done
-    OURCYGPATTERN="(^($ROOTDIRS))"
-    # Add a user-defined pattern to the cygpath arguments
-    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
-        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
-    fi
     # Now convert the arguments - kludge to limit ourselves to /bin/sh
-    i=0
-    for arg in "$@" ; do
-        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
-        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
-
-        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
-            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
-        else
-            eval `echo args$i`="\"$arg\""
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
         fi
-        i=$((i+1))
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
     done
-    case $i in
-        (0) set -- ;;
-        (1) set -- "$args0" ;;
-        (2) set -- "$args0" "$args1" ;;
-        (3) set -- "$args0" "$args1" "$args2" ;;
-        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
-        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
-        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
-        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
-        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
-        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
-    esac
 fi
 
-# Escape application args
-save () {
-    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
-    echo " "
-}
-APP_ARGS=$(save "$@")
-
-# Collect all arguments for the java command, following the shell quoting and substitution rules
-eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
-
-# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
-if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
-  cd "$(dirname "$0")"
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
 fi
 
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
 exec "$JAVACMD" "$@"
diff --git a/gradlew.bat b/gradlew.bat
index 6d57edc7..53a6b238 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -1,84 +1,91 @@
-@if "%DEBUG%" == "" @echo off
-@rem ##########################################################################
-@rem
-@rem  Gradle startup script for Windows
-@rem
-@rem ##########################################################################
-
-@rem Set local scope for the variables with windows NT shell
-if "%OS%"=="Windows_NT" setlocal
-
-set DIRNAME=%~dp0
-if "%DIRNAME%" == "" set DIRNAME=.
-set APP_BASE_NAME=%~n0
-set APP_HOME=%DIRNAME%
-
-@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-set DEFAULT_JVM_OPTS="-Xmx64m"
-
-@rem Find java.exe
-if defined JAVA_HOME goto findJavaFromJavaHome
-
-set JAVA_EXE=java.exe
-%JAVA_EXE% -version >NUL 2>&1
-if "%ERRORLEVEL%" == "0" goto init
-
-echo.
-echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
-
-goto fail
-
-:findJavaFromJavaHome
-set JAVA_HOME=%JAVA_HOME:"=%
-set JAVA_EXE=%JAVA_HOME%/bin/java.exe
-
-if exist "%JAVA_EXE%" goto init
-
-echo.
-echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
-
-goto fail
-
-:init
-@rem Get command-line arguments, handling Windows variants
-
-if not "%OS%" == "Windows_NT" goto win9xME_args
-
-:win9xME_args
-@rem Slurp the command line arguments.
-set CMD_LINE_ARGS=
-set _SKIP=2
-
-:win9xME_args_slurp
-if "x%~1" == "x" goto execute
-
-set CMD_LINE_ARGS=%*
-
-:execute
-@rem Setup the command line
-
-set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
-
-@rem Execute Gradle
-"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
-
-:end
-@rem End local scope for the variables with windows NT shell
-if "%ERRORLEVEL%"=="0" goto mainEnd
-
-:fail
-rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
-rem the _cmd.exe /c_ return code!
-if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
-exit /b 1
-
-:mainEnd
-if "%OS%"=="Windows_NT" endlocal
-
-:omega
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%"=="" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%"=="" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if %ERRORLEVEL% equ 0 goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if %ERRORLEVEL% equ 0 goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/os-integration-test/bin/.gitignore b/os-integration-test/bin/.gitignore
new file mode 100644
index 00000000..06e4d12f
--- /dev/null
+++ b/os-integration-test/bin/.gitignore
@@ -0,0 +1,2 @@
+/test/
+/main/
diff --git a/os-integration-test/build.gradle b/os-integration-test/build.gradle
index 1325e20b..167ed075 100644
--- a/os-integration-test/build.gradle
+++ b/os-integration-test/build.gradle
@@ -2,12 +2,14 @@ plugins {
     id 'groovy'
 }
 
-dependencies {
-    compile project(':core')
+repositories {
+    mavenCentral()
+}
 
-    compile 'org.spockframework:spock-core:1.2-groovy-2.5'
+dependencies {
+    implementation project(':core')
 
-    testRuntime 'ch.qos.logback:logback-classic:1.1.2'
+    testRuntimeOnly 'ch.qos.logback:logback-classic:1.4.5'
 }
 
 test {
diff --git a/os-integration-test/src/main/groovy/org/hidetake/groovy/ssh/test/os/UserManagementExtension.groovy b/os-integration-test/src/main/groovy/org/hidetake/groovy/ssh/test/os/UserManagementExtension.groovy
index 498f3a9f..3fbacedf 100644
--- a/os-integration-test/src/main/groovy/org/hidetake/groovy/ssh/test/os/UserManagementExtension.groovy
+++ b/os-integration-test/src/main/groovy/org/hidetake/groovy/ssh/test/os/UserManagementExtension.groovy
@@ -17,7 +17,7 @@ trait UserManagementExtension implements SessionExtension {
         execute "sudo passwd $user", pty: true, interaction: Helper.passwordInteraction.curry(password)
     }
 
-    private static class Helper {
+    static class Helper {
         static final passwordInteraction = { password ->
             when(partial: ~/.+[Pp]assword: */) {
                 standardInput << password << '\n'
diff --git a/server-integration-test/bin/.gitignore b/server-integration-test/bin/.gitignore
new file mode 100644
index 00000000..7ac70cd7
--- /dev/null
+++ b/server-integration-test/bin/.gitignore
@@ -0,0 +1,3 @@
+/main/
+/test/
+/default/
diff --git a/server-integration-test/build.gradle b/server-integration-test/build.gradle
index 9c58b31e..7396aa7d 100644
--- a/server-integration-test/build.gradle
+++ b/server-integration-test/build.gradle
@@ -2,21 +2,24 @@ plugins {
     id 'groovy'
 }
 
+repositories {
+    mavenCentral()
+}
+
 dependencies {
-    compile project(':core')
-    compile 'org.apache.sshd:sshd-core:2.2.0'
-    compile 'org.apache.sshd:sshd-sftp:2.2.0'
-    compile 'org.apache.sshd:sshd-scp:2.2.0'
+    implementation project(':core')
+    implementation 'org.apache.sshd:sshd-core:2.2.0'
+    implementation 'org.apache.sshd:sshd-sftp:2.2.0'
+    implementation 'org.apache.sshd:sshd-scp:2.2.0'
 
-    runtime 'org.bouncycastle:bcpkix-jdk15on:1.61'
+    runtimeOnly 'org.bouncycastle:bcpkix-jdk15on:1.61'
 
-    testCompile 'org.codehaus.groovy.modules.http-builder:http-builder:0.7.1'
+    testImplementation 'org.codehaus.groovy.modules.http-builder:http-builder:0.7.1'
 
-    testCompile 'org.spockframework:spock-core:1.2-groovy-2.5'
-    testRuntime 'cglib:cglib-nodep:3.2.10'
-    testRuntime 'org.objenesis:objenesis:3.0.1'
+    testRuntimeOnly 'cglib:cglib-nodep:3.2.10'
+    testRuntimeOnly 'org.objenesis:objenesis:3.0.1'
 
-    testRuntime 'ch.qos.logback:logback-classic:1.1.2'
+    testRuntimeOnly 'ch.qos.logback:logback-classic:1.4.5'
 }
 
 test {