title: Use environment variable in parameter section of Jenkins pipeline
body: <p>I have an environment variable which represents a gitrepo and I use this repo in my git parameter:</p>
  
  <pre><code>pipeline {
      agent any
  
      options {
          buildDiscarder(logRotator(numToKeepStr: '5', artifactNumToKeepStr: '1'))
          disableConcurrentBuilds()
      }
  
      environment {
          GitRepo = 'https://my-repo/repo.git'
      }
  
      parameters {
          gitParameter branchFilter: 'origin/(.*support.*)', defaultValue: 'develop', name: 'SUPPORTBRANCH', type: 'PT_BRANCH', useRepository: env.GitRepo , sortMode: 'DESCENDING_SMART'
      }
  ...}
  </code></pre>
  
  <p>When I use env.GitRepo inside the stages of my pipeline it works, but not when I use it in a parameter section.</p>
  
  <p>How can I make this work?</p>