Build parameters not getting propagated in Pipeline (jenkinsfile).

When using a Jenkinsfile, if I define a build parameter the parameter is not passed down into the slave/node execution so there's not way to access the values of the build parameter.

An example Jenkinsfile would be:

properties([[$class: 'ParametersDefinitionProperty', parameterDefinitions: [[$class: 'StringParameterDefinition', name: 'mode', defaultValue: 'normal']]]])
node {
  sh "env"
}

In the example above, I would expect that when I echo 'env' in my slave/node, I should see a environment variable called 'mode' with a value of 'normal' (by default). However, this is not what I see. It seems that the environment variable mode is omitted.