JavaFx RichText RunTime Error java.lang.NoClassDefFoundError: org/fxmisc/richtext/TextFlowLayout

Question

I have a runtime error for java.lang.Exception: java.lang.NoClassDefFoundError: org/fxmisc/richtext/TextFlowLayout. I'm using java14 and JavaFx13. I use Maven to download the dependencies and use the maven-assembly-plugin to package my dependencies in a single jar. I already added in require org.fxmisc.richtext in module-info.java. At design time, the class call works. But not at runtime.

Mavem:

    <dependency>
        <groupId>org.fxmisc.richtext</groupId>
        <artifactId>richtextfx</artifactId>
        <version>0.10.5</version>
    </dependency>  

The error occurs when instantiating the class in Runtime:

CodeArea codeArea = new CodeArea();

Answer 1

The MANIFEST.MF file must contain Multi-Release: true

  <archive>
    <manifestEntries>
      <Multi-Release>true</Multi-Release>
    </manifestEntries>
  </archive>

Link solution: https://github.com/FXMisc/RichTextFX/issues/966