THRIFT-2794 Suppress "unused" warnings in autogenerated Java files Client: Java

Client: java
This closes #649
diff --git a/compiler/cpp/src/generate/t_java_generator.cc b/compiler/cpp/src/generate/t_java_generator.cc
index c4cbc45..f21e8fc 100644
--- a/compiler/cpp/src/generate/t_java_generator.cc
+++ b/compiler/cpp/src/generate/t_java_generator.cc
@@ -441,7 +441,7 @@
 }
 
 string t_java_generator::java_suppressions() {
-  return "@SuppressWarnings({\"cast\", \"rawtypes\", \"serial\", \"unchecked\"})\n";
+  return "@SuppressWarnings({\"cast\", \"rawtypes\", \"serial\", \"unchecked\", \"unused\"})\n";
 }
 
 /**