Sometimes Java debugger doesn't highlight current position in decompiled class

[mmorhun]

Reproduction Steps:

1. Create a workspace from codenvy/jboss-eap7 image.
2. Clone sample kitchen sink project: https://github.com/codenvy-templates/redhat-kitchensink-webapp.git
3. Run JBoss in debug mode, compile and deploy the project.
4. Open MemberController, and set breakpoints on line:

facesContext.addMessage(null, m);

5. Connect debugger.
6. Open the application and register a user.
7. When the debugger stops on the first breakpoint use step into.

Expected behavior: Current debugger position should be highlighted.
Actual behavior: Partially decompiled class is opened, but no highlight is shown.

[mmorhun]

May be related to #5113

[ghost]

Reproduced in 5.15-SNAPSHOT

[musienko-maxim]

Depended selenium test: DebugExternalClassTest