Java function with local .jar dependency

Hi there,
I need to build a java function which uses a custom (not publicly available) jar dependency. I've added the dependency in the build.gradle file like this

    implementation 'io.appwrite:sdk-for-kotlin:4.1.0'
    implementation files('localLibs/costumJARFile.jar')
}```.
I am getting the following error when I deploy the simple starter java function.

Docker Error: Preparing for build ...
Building ...
Compiling ...
Downloading https://services.gradle.org/distributions/gradle-7.5.1-bin.zip
...........10%............20%...........30%............40%...........50%............60%...........70%............80%...........90%............100%

Welcome to Gradle 7.5.1!

Here are the highlights of this release:

• Support for Java 18
• Support for building with Groovy 4
• Much more responsive continuous builds
• Improved diagnostics for dependency resolution

For more details see https://docs.gradle.org/7.5.1/release-notes.html

Starting a Gradle Daemon (subsequent builds will be faster)

FAILURE: Build failed with an exception.

• Where:
  Build file '/usr/local/server/build.gradle' line: 7

• What went wrong:
  A problem occurred evaluating root project 'java-runtime'.

Cannot invoke method apply() on null object

• Try:

Run with --stacktrace option to get the stack trace.
Run with --info or --debug option to get more log output.
Run with --scan to get full insights.

• Get more help at https://help.gradle.org

BUILD FAILED in 53s