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

test/transform/resource/after-ecj/BuilderGenericMethod.java

@@ -0,0 +1,35 @@
+import java.util.List;
+import lombok.Builder;
+import java.util.*;
+class BuilderGenericMethod<T> {
+  public @java.lang.SuppressWarnings("all") class MapBuilder<N extends Number> {
+    private @java.lang.SuppressWarnings("all") int a;
+    private @java.lang.SuppressWarnings("all") long b;
+    @java.lang.SuppressWarnings("all") MapBuilder() {
+      super();
+    }
+    public @java.lang.SuppressWarnings("all") MapBuilder<N> a(final int a) {
+      this.a = a;
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") MapBuilder<N> b(final long b) {
+      this.b = b;
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") Map<N, T> build() {
+      return BuilderGenericMethod.this.<N>foo(a, b);
+    }
+    public @java.lang.Override @java.lang.SuppressWarnings("all") java.lang.String toString() {
+      return (((("BuilderGenericMethod.MapBuilder(a=" + this.a) + ", b=") + this.b) + ")");
+    }
+  }
+  BuilderGenericMethod() {
+    super();
+  }
+  public @Builder <N extends Number>Map<N, T> foo(int a, long b) {
+    return null;
+  }
+  public @java.lang.SuppressWarnings("all") <N extends Number>MapBuilder<N> builder() {
+    return new MapBuilder<N>();
+  }
+}