[issue #788] Add more nullity annotations where relevant

(chainable setters, static constructors, builder stuff)

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

@@ -5,10 +5,12 @@ class WithPlain {
 		this.i = i;
 		this.foo = foo;
 	}
+	@org.springframework.lang.NonNull
 	@java.lang.SuppressWarnings("all")
 	public WithPlain withI(final int i) {
 		return this.i == i ? this : new WithPlain(i, this.foo);
 	}
+	@org.springframework.lang.NonNull
 	@java.lang.SuppressWarnings("all")
 	public WithPlain withFoo(final int foo) {
 		return this.foo == foo ? this : new WithPlain(this.i, foo);