z2-Environment

See #2091

Note:

• After this we need Java 17 ((✓)
• After this we support Java 23  (✓)

Acceptance Criteria

• ECJ is upgraded (✓)
• Langlevel 23 is supported, min is 17 (✓)
• Javadoc is upgraded  (✓)

Implementation Hints¶

• Check Development Resources on how to get ECJ (✓)
• Start here https://download.eclipse.org/eclipse/downloads/
  • Version 4.35 is buggy (NPE for the unnamed module), 4.34 seems to work fine (Turns out: Bad use of the API) (✓)
• Enhance LangLevel for Java 23. (✓)
• Check for Javadoc doclet  (✓)