[feature][@CheckReturnValue] Add @lombok.CheckReturnValue to generated methods where the return value should not be ignored.

Adds the annotation to @With, @WithBy, @Builder.build(), and @SuperBuilder.build() methods. Controlled via lombok.addCheckReturnValueAnnotation config key (default: true). Static analysis tools (Error Prone, IntelliJ, SpotBugs) recognize @CheckReturnValue by simple name and will warn when the return value is discarded.

test/transform/resource/before/CheckReturnValueBuilder.java

@@ -0,0 +1,5 @@
+@lombok.Builder
+class CheckReturnValueBuilder {
+	private final int x;
+	private final String name;
+}

test/transform/resource/before/CheckReturnValueOff.java

@@ -0,0 +1,9 @@
+//CONF: lombok.addCheckReturnValueAnnotation = false
+import lombok.With;
+class CheckReturnValueOff {
+	@With final int x;
+
+	CheckReturnValueOff(int x) {
+		this.x = x;
+	}
+}

test/transform/resource/before/CheckReturnValueWith.java

@@ -0,0 +1,10 @@
+import lombok.With;
+class CheckReturnValueWith {
+	@With final int x;
+	@With final String name;
+
+	CheckReturnValueWith(int x, String name) {
+		this.x = x;
+		this.name = name;
+	}
+}