feat: avoid changing thread classloader

Author: CarstenWickner

src/main/java/io/openapitools/swagger/GenerateMojo.java

@@ -110,40 +110,29 @@ public void execute() throws MojoExecutionException, MojoFailureException {
             return;
         }
 
-        ClassLoader origClzLoader = Thread.currentThread().getContextClassLoader();
-        ClassLoader clzLoader = createClassLoader(origClzLoader);
+        Reader reader = new Reader(swaggerConfig == null ? new OpenAPI() : swaggerConfig.createSwaggerModel());
 
-        try {
-            // set the TCCL before everything else
-            Thread.currentThread().setContextClassLoader(clzLoader);
-
-            Reader reader = new Reader(swaggerConfig == null ? new OpenAPI() : swaggerConfig.createSwaggerModel());
+        JaxRSScanner reflectiveScanner = new JaxRSScanner(getLog(), createClassLoader(), resourcePackages, useResourcePackagesChildren);
 
-            JaxRSScanner reflectiveScanner = new JaxRSScanner(getLog(), resourcePackages, useResourcePackagesChildren);
+        Application application = resolveApplication(reflectiveScanner);
+        reader.setApplication(application);
 
-            Application application = resolveApplication(reflectiveScanner);
-            reader.setApplication(application);
+        OpenAPI swagger = OpenAPISorter.sort(reader.read(reflectiveScanner.classes()));
 
-            OpenAPI swagger = OpenAPISorter.sort(reader.read(reflectiveScanner.classes()));
-
-            if (outputDirectory.mkdirs()) {
-                getLog().debug("Created output directory " + outputDirectory);
-            }
+        if (outputDirectory.mkdirs()) {
+            getLog().debug("Created output directory " + outputDirectory);
+        }
 
-            outputFormats.forEach(format -> {
-                try {
-                    File outputFile = new File(outputDirectory, outputFilename + "." + format.name().toLowerCase());
-                    format.write(swagger, outputFile, prettyPrint);
-                    if (attachSwaggerArtifact) {
-                        projectHelper.attachArtifact(project, format.name().toLowerCase(), "swagger", outputFile);
-                    }
-                } catch (IOException e) {
-                    throw new RuntimeException("Unable write " + outputFilename + " document", e);
+        try {
+            for (OutputFormat format : outputFormats) {
+                File outputFile = new File(outputDirectory, outputFilename + "." + format.name().toLowerCase());
+                format.write(swagger, outputFile, prettyPrint);
+                if (attachSwaggerArtifact) {
+                    projectHelper.attachArtifact(project, format.name().toLowerCase(), "swagger", outputFile);
                 }
-            });
-        } finally {
-            // reset the TCCL back to the original class loader
-            Thread.currentThread().setContextClassLoader(origClzLoader);
+            }
+        } catch (IOException e) {
+            throw new RuntimeException("Unable write " + outputFilename + " document", e);
         }
     }
 
@@ -164,15 +153,15 @@ private Application resolveApplication(JaxRSScanner reflectiveScanner) {
         return ClassUtils.createInstance(appClazz);
     }
 
-    private URLClassLoader createClassLoader(ClassLoader parent) {
+    private URLClassLoader createClassLoader() {
         try {
             Collection<String> dependencies = getDependentClasspathElements();
             URL[] urls = new URL[dependencies.size()];
             int index = 0;
             for (String dependency : dependencies) {
                 urls[index++] = Paths.get(dependency).toUri().toURL();
             }
-            return new URLClassLoader(urls, parent);
+            return new URLClassLoader(urls, Thread.currentThread().getContextClassLoader());
         } catch (MalformedURLException e) {
             throw new RuntimeException("Unable to create class loader with compiled classes", e);
         } catch (DependencyResolutionRequiredException e) {

src/main/java/io/openapitools/swagger/JaxRSScanner.java

@@ -2,7 +2,6 @@
 
 import java.util.Collections;
 import java.util.HashSet;
-import java.util.List;
 import java.util.Set;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
@@ -26,42 +25,48 @@ class JaxRSScanner {
 
     private final Log log;
 
+    private final ClassGraph classGraph;
+
     private final Set<String> resourcePackages;
 
     private final boolean useResourcePackagesChildren;
 
-    public JaxRSScanner(Log log, Set<String> resourcePackages, Boolean useResourcePackagesChildren) {
+    public JaxRSScanner(Log log, ClassLoader clzLoader, Set<String> resourcePackages, Boolean useResourcePackagesChildren) {
         this.log = log;
+        this.classGraph = new ClassGraph().enableClassInfo().enableAnnotationInfo()
+                .addClassLoader(clzLoader);
         this.resourcePackages = resourcePackages == null ? Collections.emptySet() : new HashSet<>(resourcePackages);
         this.useResourcePackagesChildren = Boolean.TRUE.equals(useResourcePackagesChildren);
     }
 
     Application applicationInstance() {
-        ClassGraph classGraph = new ClassGraph().enableClassInfo();
+        Application applicationInstance = null;
         try (ScanResult scanResult = classGraph.scan()) {
-            List<ClassInfo> applicationClasses = scanResult.getSubclasses(Application.class.getName()).stream()
-                    .filter(this::filterClassByResourcePackages)
-                    .collect(Collectors.toList());
+            ClassInfoList applicationClasses = scanResult.getSubclasses(Application.class.getName())
+                    .filter(this::filterClassByResourcePackages);
             if (applicationClasses.size() == 1) {
-                return ClassUtils.createInstance(applicationClasses.get(0).loadClass(Application.class));
-            }
-            if (applicationClasses.size() > 1) {
+                applicationInstance = ClassUtils.createInstance(applicationClasses.get(0).loadClass(Application.class));
+            } else if (applicationClasses.size() > 1) {
                 log.warn("More than one javax.ws.rs.core.Application classes found on the classpath, skipping");
             }
         }
-        return null;
+        return applicationInstance;
     }
 
     Set<Class<?>> classes() {
-        ClassGraph classGraph = new ClassGraph().enableClassInfo().enableAnnotationInfo();
+        Set<Class<?>> classes;
         try (ScanResult scanResult = classGraph.scan()) {
             ClassInfoList apiClasses = scanResult.getClassesWithAnnotation(Path.class.getName());
             ClassInfoList defClasses = scanResult.getClassesWithAnnotation(OpenAPIDefinition.class.getName());
-            return Stream.concat(apiClasses.stream(), defClasses.stream())
-                    .filter(this::filterClassByResourcePackages)
+            classes = Stream.of(apiClasses, defClasses)
+                    .flatMap(classList -> classList.filter(this::filterClassByResourcePackages).stream())
                     .map(ClassInfo::loadClass)
                     .collect(Collectors.toSet());
         }
+        if (classes.isEmpty()) {
+            log.warn("No @Path or @OpenAPIDefinition annotated classes found in given resource packages: " + resourcePackages);
+        }
+        return classes;
     }
 
     private boolean filterClassByResourcePackages(ClassInfo cls) {