java.lang.IllegalArgumentException: file:/Users/alvin/.gradle/caches/modules-2/files-2.1/antlr/antlr/2.7.7/da39a3ee5e6b4b0d3255bfef95601890afd80709/antlr-2.7.7-sources.jar is not a valid classpath entry; use a jar-protocol URL.
   at org.netbeans.modules.java.classpath.SimplePathResourceImplementation.verify(SimplePathResourceImplementation.java:104)
   at org.netbeans.modules.java.classpath.SimplePathResourceImplementation.verify(SimplePathResourceImplementation.java:68)
   at org.netbeans.modules.java.classpath.SimplePathResourceImplementation.<init>(SimplePathResourceImplementation.java:131)
   at org.netbeans.spi.java.classpath.support.ClassPathSupport.createResource(ClassPathSupport.java:77)
   at org.netbeans.spi.java.classpath.support.ClassPathSupport.createClassPath(ClassPathSupport.java:126)
   at org.netbeans.api.java.source.SourceUtils.getFile(SourceUtils.java:526)
   at org.netbeans.modules.editor.java.JavaCompletionProvider$JavaCompletionQuery.query(JavaCompletionProvider.java:206)
   at org.netbeans.spi.editor.completion.support.AsyncCompletionTask.run(AsyncCompletionTask.java:223)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1443)
   at org.netbeans.modules.openide.util.GlobalLookup.execute(GlobalLookup.java:68)
   at org.openide.util.lookup.Lookups.executeWith(Lookups.java:303)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2058)