There are 2 questions ：

1。 pipeline/freestylejob cannot get empty param value。
2。 pipeline under docker agent can  get empty param value。

I define the pipelie with parameter like below

parameters {
     string(name: 'ANDROID_PLATFORM', defaultValue: '')
}

in stage i try to print this parameter 'ANDROID_PLATFORM', like below

stage("0.clean ws") {
steps {
  sh '''#!/bin/bash
env
'''
}
}

start this pipeline with empty string ANDROID_PLATFORM, the env command not print this value.
in python code i try to get ANDROID_PLATFORM like this

  os.environ.get("ANDROID_PLATFORM")

but this return None.I want this return "", an empty string value。

workaround in python maybe work well like this：

  os.environ.get("ANDROID_PLATFORM", "")