Project Level Extra Properties in Gradle Script

We can have project level 'extra' properties in gradle. These properties are accessible throughout the script.
To set some properties, we can do it as

project.ext {
  myVar = "A variable"
  isProcessStarted = null
}

Some examples of using these properties are given below.

/** Task which starts some process */
task startProcess() << {
  project.isProcessStarted = true
}
/** Task which stops a process */
task stopProcess() << {
  project.isProcessStarted = false
}
/* Stop the process only if the process was started */
stopProcess.onlyIf { project.isProcessStarted == true }