[REQ] Just can't make this work

I am so sorry to open up an issue because of this but idk why I am simply not getting how I am supposed to use the generator.

Note: Just found https://github.com/OpenAPITools/openapi-generator/pull/9059, https://github.com/OpenAPITools/openapi-generator/issues/8591 (might be related)

What I intend to do is have different tasks in order to generate clients in different languages.

So for example, I'd like to specify one task for Angular and another for Java, something like this:

openApiGenerate {
    inputSpec swaggerFilePath
}

task buildTypeScriptAngular(type: org.openapitools.generator.gradle.plugin.tasks.GenerateTask) {
    generatorName = "typescript-angular"
    outputDir = "$apiClientOutputDir/angular"
    configOptions = [
            npmName   : "$name-rest-client",
            npmVersion: '0.0.0',
            ngVersion : '11.0.6'
    ]
}

task buildJava(type: org.openapitools.generator.gradle.plugin.tasks.GenerateTask) {
    generatorName = "java"
    outputDir = "$apiClientOutputDir/java"
}

However, I'm struggling with openApiGenrate from the start. If I am writing:

openApiGenerate {
    inputSpec swaggerFilePath
}

I'd get

A problem occurred evaluating root project 'server-client-template'.
> No signature of method: build_8cj7fyrw9t67hxobm8609uql7.openApiGenerate() is applicable for argument types: (build_8cj7fyrw9t67hxobm8609uql7$_run_closure7) values: [build_8cj7fyrw9t67hxobm8609uql7$_run_closure7@5c2cd655]

If I am using the assignment operator

openApiGenerate {
    inputSpec = swaggerFilePath
}

I'd get the following error

A problem was found with the configuration of task ':openApiGenerate' (type 'GenerateTask').
  - In plugin 'org.openapi.generator' type 'org.openapitools.generator.gradle.plugin.tasks.GenerateTask' property 'input' annotated with @Internal should not be also annotated with @Input.

I cannot find a simple example on how to do this properly. Can somebody please tell me how this works - it really gets frustrating.

Start with the Gradle plugin's GenerateTask configuration and compare the two error cases with pull request 9059 and issue 8591. Document a minimal working example for one generation task and separate Angular and Java tasks; it is done when the examples configure without the reported Gradle errors.