Javadoc is taken from a JAR (Maven dependency) instead of the currently open file

The Javadoc window displays the Javadoc of the current file. But after having opened a file with the same package and class name from a Maven dependency, the Javadoc window displays the Javadoc from the dependency, even after that file was closed.

Steps to reproduces:

1. Create a Maven project
2. Add a dependency
3. Download Javadoc and sources for the dependency
4. Open one of the dependency’s files
5. Save the source file in your local filesystem
6. Open the copy and modify the Javadoc

Expected result:

Javadoc window should show your modifications

Actual result:

Javadoc window still shows the Javadoc from the JAR.

After restarting NetBeans, the modified Javadoc is shown, but it is replaced with the text from the JAR after a few seconds (during “Refreshing indices”).