Fix userId type when using OAuth 2.0

[mraible]

Fixes #14328.

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[mraible]

Is webflux-mariadb-gradle because of bintray? I know it's going away soon.

* What went wrong:
A problem occurred configuring root project 'sample-webflux-maria'.
> Could not resolve all artifacts for configuration ':classpath'.
   > Could not resolve com.fasterxml.jackson.datatype:jackson-datatype-joda:2.12.1.
     Required by:
         project : > org.openapi.generator:org.openapi.generator.gradle.plugin:4.3.1 > org.openapitools:openapi-generator-gradle-plugin:4.3.1 > org.openapitools:openapi-generator:4.3.1
      > Could not resolve com.fasterxml.jackson.datatype:jackson-datatype-joda:2.12.1.
         > Could not get resource 'plugins.gradle.org/m2/com/fasterxml/jackson/datatype/jackson-datatype-joda/2.12.1/jackson-datatype-joda-2.12.1.module'.
            > Could not GET 'jcenter.bintray.com/com/fasterxml/jackson/datatype/jackson-datatype-joda/2.12.1/jackson-datatype-joda-2.12.1.module'.
               > Read timed out
   > Could not resolve com.fasterxml.jackson.datatype:jackson-datatype-joda:2.12.1.
     Required by:
         project : > com.google.cloud.tools.jib:com.google.cloud.tools.jib.gradle.plugin:2.8.0 > gradle.plugin.com.google.cloud.tools:jib-gradle-plugin:2.8.0 > com.fasterxml.jackson.core:jackson-databind:2.12.1 > com.fasterxml.jackson:jackson-bom:2.12.1
      > Could not resolve com.fasterxml.jackson.datatype:jackson-datatype-joda:2.12.1.
         > Could not get resource 'plugins.gradle.org/m2/com/fasterxml/jackson/datatype/jackson-datatype-joda/2.12.1/jackson-datatype-joda-2.12.1.module'.
            > Could not GET 'jcenter.bintray.com/com/fasterxml/jackson/datatype/jackson-datatype-joda/2.12.1/jackson-datatype-joda-2.12.1.module'.
               > Read timed out

[atomfrede]

Not sure how far the gradle plugin migration has come, but maybe removing gradlePluginPortal() from our build.gradle might help, when reading https://blog.gradle.org/jcenter-shutdown, although I am not sure any plugin can be resolved afterwards. At least the jib plugin has still jcenter() in their source code so maybe we can't do something about their internal dependency resolution.

[mraible]

@atomfrede I'll try running all the jobs again to see if that helps.