SuppressWarningsWithoutExplanation
Use of @SuppressWarnings should be accompanied by a comment describing why the warning is safe to ignore.

Severity
WARNING
Tags
Style

The problem

Suppressions for unchecked or rawtypes warnings should have an accompanying comment to explain why the javac warning is safe to ignore.

Rather than just suppressing the warning:

@SuppressWarnings("unchecked")
public ImmutableList<Object> performScaryCast(ImmutableList<String> strings) {
  return (ImmutableList<Object>) (ImmutableList<?>) strings;
}

Provide a concise explanation for why it is safe:

@SuppressWarnings("unchecked") // Safe covariant cast, given ImmutableList cannot be added to.
public ImmutableList<Object> performScaryCast(ImmutableList<String> strings) {
  return (ImmutableList<Object>) (ImmutableList<?>) strings;
}

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("SuppressWarningsWithoutExplanation") to the enclosing element.