[Java] Cast return of numInGroup to an int so that uint32 can be supported to a limited extent.

Author: mjpt777

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/java/JavaGenerator.java

@@ -354,7 +354,7 @@ private void generateGroupDecoderClassHeader(
             indent + "        this.buffer = buffer;\n" +
             indent + "        dimensions.wrap(buffer, parentMessage.limit());\n" +
             indent + "        blockLength = dimensions.blockLength();\n" +
-            indent + "        count = dimensions.numInGroup();\n" +
+            indent + "        count = (int)dimensions.numInGroup();\n" +
             indent + "        index = -1;\n" +
             indent + "        parentMessage.limit(parentMessage.limit() + HEADER_SIZE);\n" +
             indent + "    }\n\n",