support for @Builder on methods with a generified return type. Fixes #1420

test/transform/resource/before/BuilderGenericMethod.java

@@ -0,0 +1,11 @@
+import java.util.List;
+
+import lombok.Builder;
+import java.util.*;
+
+class BuilderGenericMethod<T> {
+	@Builder
+	public <N extends Number> Map<N,T> foo(int a, long b) {
+		return null;
+	}
+}