[REQ][openapi-generator-gradle-plugin] Control log level for Java generator

Is your feature request related to a problem? Please describe.

As a user of the openapi-generator-gradle-plugin,
I would like to be able to control the log.level of the java generator,
So that I can suppress warning log entries like Multiple schemas found in the OAS 'content' section, returning only the first one (text/plain).

Describe the solution you'd like

This configuration could potentially be provided like so:

task buildMyClient(type: org.openapitools.generator.gradle.plugin.tasks.GenerateTask) {
    generatorName = "java"
    ...
    configOptions = [
            ....
            logLevel: "error"
    ]

Additional Context

At the moment, the openapi-generator generates a lot of warn level output on valid schemas, that we do not own and cannot alter anyway. This log output creates a lot of noise in our gradle builds and potentially a slight build performance overhead. Example output:

Multiple schemas found in the OAS 'content' section, returning only the first one (text/plain)
Multiple schemas found in the OAS 'content' section, returning only the first one (application/json-patch+json)
Empty operationId found for path: post /api/User/Email. Renamed to auto-generated operationId: apiUserEmailPost
Multiple schemas found in the OAS 'content' section, returning only the first one (text/plain)
Multiple schemas found in the OAS 'content' section, returning only the first one (text/plain)
Multiple schemas found in the OAS 'content' section, returning only the first one (application/json-patch+json)

Start by inspecting the openapi-generator-gradle-plugin's GenerateTask and how its configOptions reach the Java generator. Check the existing log-level handling, then verify that a logLevel of "error" suppresses warning output during generation without hiding errors.