Change AbstractServiceDescriptor.methods() to Collection. Resolves #573
diff --git a/compiler/src/test/golden/TestService.java.txt b/compiler/src/test/golden/TestService.java.txt
index cb3baf6..a8b4f47 100644
--- a/compiler/src/test/golden/TestService.java.txt
+++ b/compiler/src/test/golden/TestService.java.txt
@@ -121,7 +121,7 @@
     }
 
     @java.lang.Override
-    public com.google.common.collect.ImmutableList<io.grpc.MethodDescriptor<?, ?>> methods() {
+    public java.util.Collection<io.grpc.MethodDescriptor<?, ?>> methods() {
       return com.google.common.collect.ImmutableList.<io.grpc.MethodDescriptor<?, ?>>of(
           unaryCall,
           streamingOutputCall,