title: Jenkins Pipeline: build job with default paramter value if value not supplied
body: <p>I have a Jenkins pipeline job that accepts 1 parameter with default value.
  This job is building another job passing the parameter value.</p>
  
  <p>Code of parent job:</p>
  
  <pre><code>node
  {
      stage ('build job_1')
      {
          build job: 'job_1',
          parameters: [[$class: 'StringParameterValue', name: 'DROP_LOC', value: 'default_value']]
      }
  }
  </code></pre>
  
  <p>Expected behaviour:</p>
  
  <ol>
  <li><p>If parent job get DROP_LOC parameter value, it should use it to build job_1</p></li>
  <li><p>If parent job has no DROP_LOC parameter value, it should use the default value to build job_1</p></li>
  </ol>
  
  <p>Please help how to do that? What is the correct code?</p>