code: static FormattingTuple format(String messagePattern, Object arg) {
          return arrayFormat(messagePattern, new Object[]{arg});
      }
docs: Performs single argument substitution for the 'messagePattern' passed as
  parameter.
  <p/>
  For example,
  <p/>
  <pre>
  MessageFormatter.format(&quot;Hi {}.&quot;, &quot;there&quot;);
  </pre>
  <p/>
  will return the string "Hi there.".
  <p/>
  
  @param messagePattern The message pattern which will be parsed and formatted
  @param arg            The argument to be substituted in place of the formatting anchor
  @return The formatted message