AVRO-1869: Java: Fix Decimal conversion from ByteBuffer.

Author: rdblue

CHANGES.txt

@@ -15,6 +15,8 @@ Trunk (not yet released)
     AVRO-1741: Python3: Fix error when codec is not in the header.
     (Matthew Hayes via blue)
 
+    AVRO-1869: Java: Fix Decimal conversion from ByteBuffer. (blue)
+
 Avro 1.8.1 (14 May 2016)
 
   INCOMPATIBLE CHANGES

lang/java/avro/src/main/java/org/apache/avro/Conversions.java

@@ -80,7 +80,8 @@ public String getLogicalTypeName() {
     public BigDecimal fromBytes(ByteBuffer value, Schema schema, LogicalType type) {
       int scale = ((LogicalTypes.Decimal) type).getScale();
       // always copy the bytes out because BigInteger has no offset/length ctor
-      byte[] bytes = value.get(new byte[value.remaining()]).array();
+      byte[] bytes = new byte[value.remaining()];
+      value.get(bytes);
       return new BigDecimal(new BigInteger(bytes), scale);
     }