There are some properties that I wish were set globally for all of my jobs/nodes.    I wish to control this in one place and be additive to what might already be set in that job/node for the user.  ie: mvn_user, mvn_password

Our current example is setting the maven username and password for our private Nexus OSS repo.  I am certain this can expand to other use cases.  

Expected:
Jenkins Configuration Section
Gradle Project Configuration
    gradle.properties: [ADD PROPERTY] 
     <?> = Adds or Edits properties found in ~/.gradle/gradle.properties for the running job.   If the property is not present it will be added.  If the property is present it will be edited to have this value.  

  [ADD PROPERTY] type: user/pass  (button for adding a user giving the option to set the key name for each part...user and password
  [ADD PROPERTY] type: key/value (two text boxes on for key and one for value)

  [ADD PROPERTY] type: script (allows for runtime groovy script to be executed and properties to be added after script logic generates keys and values.