LambdaIsMethodReference mutator could introduce side effects

[mches]

An expression lambda like s -> b.append("/").append(s) can't be converted to a method reference because b.append("/") has a side effect

String a = null;
StringBuilder b = new StringBuilder();
Optional.ofNullable(a).ifPresent(s -> b.append("/").append(s));
System.out.println(b);

Output:

↓↓↓

String a = null;
StringBuilder b = new StringBuilder();
Optional.ofNullable(a).ifPresent(b.append("/")::append);
System.out.println(b);

Output:

/

Seems safer to assume a call chain produces a side effect and give up on converting such a lambda expression to method reference.

[blacelle]

Fixed in #849

[mches]

Bravo! 👏🏻