The plugin cannot find jflex generated java source code.

The plugin cannot correctly resolve OpenGrok's generated Java source.

Environment

• Operating System: Ubuntu 18.04
• JDK version: OpenJDK 11 64 Bit
• Visual Studio Code version: 1.33.1
• Java extension version: 0.43.0

Steps To Reproduce

1. git clone git@github.com:oracle/opengrok.git
2. Use VS Code open the folder.

Example project: OpenGrok

Current Result

Lots of errors like this one

{
	"resource": "/home/shenghang/code/opengrok/opengrok-indexer/src/main/java/org/opengrok/indexer/analysis/ada/AdaAnalyzer.java",
	"owner": "_generated_diagnostic_collection_name_#1",
	"code": "16777218",
	"severity": 8,
	"message": "AdaXref cannot be resolved to a type",
	"source": "Java",
	"startLineNumber": 68,
	"startColumn": 34,
	"endLineNumber": 68,
	"endColumn": 41
}

Expected Result

The project can be correctly parsed.

Additional Informations

The code that cannot be resolved is on opengrok-indexer/target/generated-sources/jflex/org/opengrok/indexer/analysis folder.

Reproduce the problem by cloning OpenGrok and opening it in VS Code. Start with opengrok-indexer/src/main/java/org/opengrok/indexer/analysis/ada/AdaAnalyzer.java and the generated sources under opengrok-indexer/target/generated-sources/jflex/org/opengrok/indexer/analysis. Done means the generated Java types are resolved and the project no longer reports these diagnostics.