code: public static String unwrap(final String str, final char wrapChar) {
          if (isEmpty(str) || wrapChar == CharUtils.NUL) {
              return str;
          }
  
          if (str.charAt(0) == wrapChar && str.charAt(str.length() - 1) == wrapChar) {
              final int startIndex = 0;
              final int endIndex = str.length() - 1;
              if (endIndex != -1) {
                  return str.substring(startIndex + 1, endIndex);
              }
          }
  
          return str;
      }
docs: <p>
  Unwraps a given string from a character.
  </p>
  
  <pre>
  StringUtils.unwrap(null, null)         = null
  StringUtils.unwrap(null, '\0')         = null
  StringUtils.unwrap(null, '1')          = null
  StringUtils.unwrap("\'abc\'", '\'')    = "abc"
  StringUtils.unwrap("AABabcBAA", 'A')  = "ABabcBA"
  StringUtils.unwrap("A", '#')           = "A"
  StringUtils.unwrap("#A", '#')          = "#A"
  StringUtils.unwrap("A#", '#')          = "A#"
  </pre>
  
  @param str
  the String to be unwrapped, can be null
  @param wrapChar
  the character used to unwrap
  @return unwrapped String or the original string
  if it is not quoted properly with the wrapChar
  @since 3.6