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

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

@@ -0,0 +1,40 @@
+import java.util.List;
+import java.util.*;
+class BuilderGenericMethod<T> {
+	public <N extends Number> Map<N, T> foo(int a, long b) {
+		return null;
+	}
+	@java.lang.SuppressWarnings("all")
+	public class MapBuilder<N extends Number> {
+		@java.lang.SuppressWarnings("all")
+		private int a;
+		@java.lang.SuppressWarnings("all")
+		private long b;
+		@java.lang.SuppressWarnings("all")
+		MapBuilder() {
+		}
+		@java.lang.SuppressWarnings("all")
+		public MapBuilder<N> a(final int a) {
+			this.a = a;
+			return this;
+		}
+		@java.lang.SuppressWarnings("all")
+		public MapBuilder<N> b(final long b) {
+			this.b = b;
+			return this;
+		}
+		@java.lang.SuppressWarnings("all")
+		public Map<N, T> build() {
+			return BuilderGenericMethod.this.<N>foo(a, b);
+		}
+		@java.lang.Override
+		@java.lang.SuppressWarnings("all")
+		public java.lang.String toString() {
+			return "BuilderGenericMethod.MapBuilder(a=" + this.a + ", b=" + this.b + ")";
+		}
+	}
+	@java.lang.SuppressWarnings("all")
+	public <N extends Number> MapBuilder<N> builder() {
+		return new MapBuilder<N>();
+	}
+}