title: Why does IntToDoubleFunction not come with IntToDoubleFunction andThen(DoubleUnaryOperator after)
body: <p>Why does <a href="http://download.java.net/jdk8/docs/api/java/util/function/DoubleUnaryOperator.html" rel="nofollow">DoubleUnaryOperator</a> come with default implementations for composition like</p>
  
  <p><code>DoubleUnaryOperator andThen(DoubleUnaryOperator after);</code></p>
  
  <p>but <a href="http://download.java.net/jdk8/docs/api/java/util/function/IntToDoubleFunction.html" rel="nofollow">IntToDoubleFunction</a> does not (as of b124, assumed to be feature complete). Is there a special reason that IntToDoubleFunction does not have a</p>
  
  <p><code>IntToDoubleFunction andThen(DoubleUnaryOperator after);</code>
  ?</p>