code: public static String trimToNull(String str) {
          String ts = trim(str);
          return isEmpty(ts) ? null : ts;
      }
docs: <pre>
  StringUtils.trimToNull(null)          = null
  StringUtils.trimToNull("")            = null
  StringUtils.trimToNull("     ")       = null
  StringUtils.trimToNull("abc")         = "abc"
  StringUtils.trimToNull("    abc    ") = "abc"
  </pre>
  
  @param str the String to be trimmed, may be null
  @return the trimmed String,
  {@code null} if only chars &lt;= 32, empty or null String input
  @since 2.0