Problems with configuration caching caused by build-parameters plugin are fixed

[britter]

When building this project I frequently see the following log message:

❯ ./gradlew check
Configuration cache is an incubating feature.
Calculating task graph as configuration cache cannot be reused because an input to task ':plugins:build-parameters:jar' has changed.

What this means is that due to the application of the released build-parameters plugin to this project, the configuration cache can not be reused sometimes. It looks like the plugin we're building produces unstable outputs. Me first guess is that we're using collections that produce unstable outputs somewhere, e.g a HashMap.