code: public TypeParserBuilder unregisterParser(Class<?> targetType) {
          if (targetType == null) {
              throw new NullPointerException(makeNullArgumentErrorMsg("targetType"));
          }
          parsers.remove(targetType);
          return this;
      }
docs: Unregister the {@link Parser} associated with the given {@code targetType}.
  {@code targetType} will be ignored if not associated with any {@link Parser}.
  
  @param targetType The type associated with {@link Parser} to unregister.
  @return {@link TypeParserBuilder}
  @throws NullPointerException if given argument is null.