title: antlr4: ATN version 2 expected 3
body: <p>When trying to use a generated grammar and lexer I get: </p>
  
  <blockquote>
    <p>org.antlr.v4.runtime.atn.ATN; Could not deserialize ATN with version 2 (expected 3).</p>
  </blockquote>
  
  <p>What's wrong? </p>