title: What does this "R" mean in the Java debugger?
body: <p><a href="https://i.stack.imgur.com/QzVTN.png" rel="nofollow noreferrer">I got this by debugging in Tomcat</a>.</p>
  
  <p>It seems to be a java bytecode descriptor, but I've looked up the reference
  <a href="https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html" rel="nofollow noreferrer">https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html</a> and there is no field descriptor "R".</p>
  
  <p>Any answers would be appreciated!</p>