The asset metadata is invalid, There was an error while trying to extract the metadata for extension" error using Maven

SYMPTOM

While deploying a custom connector asset to Exchange using Maven, it fails with "The asset metadata is invalid, There was an error while trying to extract the metadata for extension" error message:

2023-10-02 12:19:35:304 [main] [DEBUG] An error occurred while loading the Extension descriptions file
(...)
Caused by: java.lang.RuntimeException: Publication ended with errors: [The asset metadata is invalid, There was an error while trying to extract the metadata for extension: { groupId: ***, assetId: mulesoft-custom-connector, version: 1.0.0 }]

CAUSE

The error comes from Exchange platform when trying to compile with JDK 8 and finding an error. Custom connectors are developed using the Mule SDK, and need to be compile with JDK 8 as stated in MuleSoft documentation:

The maximum supported version for Java SDK is JDK 11, however, you can use JDK 11 only for running your application. Compilation with Java SDK must be done with JDK 8.

If there was no issue shown during development is because the local machine was using a higher Java JDK version.
 

SOLUTION

Make the customer connector compile with JDK 8 by removing dependencies that need newest Java versions.