title: Java regex to split text in first line and all remaining lines
body: <p>Given a multiline text string consisting of several lines (including blank ones), what would be the most efficient regex to</p>
  
  <ol>
  <li>Fully match the string, and</li>
  <li>Split the string in 2 groups, consisting of the first line and everything that follows, respectively?</li>
  </ol>
  
  <p>Trying a simple expression like</p>
  
  <pre><code>(?m)(.*)((?:\s|.)*)
  </code></pre>
  
  <p>does not work beyond a certain string length (just a few hundred characters), causing a stack overflow (!). Many variations afterwards, the same issue persists...</p>