code: public String substring(final Object target, final int start) {
          if (target == null) {
              return null;
          }
          return StringUtils.substring(target, start);
      }
docs: <p>
  copy a part of target start beginIndex to the end of target.
  If non-String object, toString() will be called.
  </p>
  @param target  source of the copy.
  @param start   index where the copy start.
  
  @return part of target, or {@code null} if target is null.
  
  @since 1.1.2