private DeclaredType collectionOf(TypeMirror elementType) {
      return types.getDeclaredType(elements.getTypeElement("java.util.Collection"), elementType);
    }
Parameter object to simplify the branches of {@link #format(CodeBlock, CodeBlock,
TypeMirror)} that call a delegate method.
value/src/main/java/com/google/auto/value/extension/toprettystring/processor/ToPrettyStringExtension.java