title: IntelliJ IDEA won't step into method in third party jar
body: <p>I'm using IntelliJ IDEA 14.1.5 to step through a Java program that calls methods in a third party jar (JTidy).</p>
  
  <p>The source for this jar is attached; if I highlight one of its methods and press <code>ctrl-B</code> to go to its declaration, IDEA goes there correctly.</p>
  
  <p>I set a breakpoint within this method, on a statement I know is executing.</p>
  
  <p>I turned off <em>all</em> stepping filters under Settings > Build, Execution Deployment > Debugger > Stepping.</p>
  
  <p>Stepping into methods in the JCL, such as <code>java.lang.String.append()</code>, works properly.</p>
  
  <p>Stepping into this third party jar, however, will not work. Even Force Step Into does not work. The breakpoint within that code also doesn't work; the whole method is treated as a Step Over, which means I can't look at the exact point in the process I need to inspect.</p>
  
  <p>What do I have to check to get this working? It's plausible that attaching the source would not necessarily enable debugging on that code, except that there is at least <a href="https://stackoverflow.com/questions/3610576/java-netbeans-how-to-step-into-a-jar-file">one other answer on another SO question that suggests that this should work</a>. So does a Tip in <a href="https://www.jetbrains.com/help/idea/2016.2/choosing-a-method-to-step-into.html" rel="nofollow noreferrer">IntelliJ's documentation on debugging</a>.</p>