We are uanble to get value of the label parameter as variable when used in the jenkins pipeline 

Here we are declaring TEST_CLIENT as the label parameter in jenkins. When we try to use it the value of label parameter is null in the parameter 

using it as 

pipeline {
agent {
node

}

When trying to echo the value of Label Parameter is null using env and params

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env.TEST_CLIENT: class org.codehaus.groovy.runtime.NullObject
[Pipeline] echo
params.TEST_CLIENT: class org.codehaus.groovy.runtime.NullObject