Added tests to check warnings/errors emitted by Builder.Default support.

test/transform/resource/before/BuilderDefaultsWarnings.java

@@ -1,8 +1,18 @@
 import lombok.Builder;
+import lombok.Singular;
 
 @Builder
 public class BuilderDefaultsWarnings {
 	long x = System.currentTimeMillis();
 	final int y = 5;
 	@Builder.Default int z;
+	@Builder.Default @Singular java.util.List<String> items;
+}
+
+class NoBuilderButHasDefaults {
+	@Builder.Default private final long z = 5;
+	
+	@Builder
+	public NoBuilderButHasDefaults() {
+	}
 }