@Override
    public String toString() {
      return identifier;
    }
Returns the name of the property as it should be used when declaring identifiers (fields and
parameters). If the original getter method was {@code foo()} then this will be {@code foo}.
If it was {@code getFoo()} then it will be {@code foo}. If it was {@code getPackage()} then
it will be something like {@code package0}, since {@code package} is a reserved word.
value/src/main/java/com/google/auto/value/processor/AutoValueishProcessor.java