StringBuilder with constant number of args can be replaced with concatenation

[carterkozak]

What happened?

StringBuilder usage with a constant number of arguments can be replaced with simple string concatenation (+ operator).

See the discussion on palantir/conjure-java#555

Compiling for a java 8 target results in the same bytecode, and applications which target java 9+ take advantage of JEP 280 for a more efficient codepath.

String value = new StringBuilder().append("foo").append(bar).toString();

Can be replaced with

String value = "foo" + bar;

What did you want to happen?

We can build an errorprone check with either a suggested fix, or a refaster rule to automatically replace these in existing code.