Change for handling "+" signs in the parameter.

Camunda Keycloak Identity Provider Pull Request

Description

[x] Bug fix (non-breaking change which fixes an existing open issue)
[ ] New feature (non-breaking change which adds functionality to an extension)
[ ] Breaking change (fix or feature that would cause existing functionality of an extension to change)
[ ] Documentation update (changes made to an existing piece of documentation)

[x] My code adheres to the syntax used by this extension.
[ ] My pull request requires a change to the documentation.
[ ] I have updated the documentation accordingly.
[x] I have read the Camunda Community Hub documentation
[ ] I have read the Pull Request Process documentation
[ ] I have added or suggested tests to cover my changes suggested in this pull request.
[ ] All new and existing CI/CD tests passed.
[ ] I will /assign myself this issue, and add the relevant [issue labels] to it if they are not automatically generated by Probot.
[ ] I will tag @celanthe in a new comment on this issue if 30 days have passed since my pull request was opened and I have not received a response from the extension's Maintainer