code: public static String ensureLeft(final String value, final String prefix, final boolean caseSensitive) {
          validate(value, NULL_STRING_PREDICATE, NULL_STRING_MSG_SUPPLIER);
          if (caseSensitive) {
              return value.startsWith(prefix) ? value : prefix + value;
          }
          String _value = value.toLowerCase();
          String _prefix = prefix.toLowerCase();
          return _value.startsWith(_prefix) ? value : prefix + value;
      }
docs: Ensures that the value begins with prefix. If it doesn't exist, it's prepended.
  
  @param value         input
  @param prefix        prefix
  @param caseSensitive true or false
  @return string with prefix if it was not present.