What does this symbol mean in IntelliJ? (red circle on bottom-left corner of file name, with 'J' in it)

Question

Under the target folder in IntelliJ for a Java project I created, I have a few java source files in the package. Beside each file the \'J\' icon has a red circle with a lin

Answer 1

For a gradle project "./gradlew --stop" will help to resolve the problem when the source directory is correctly specified and project is properly synced.