The projectDir is invisible from the task class in Gradle script - class

Question

It is an example of a build.gradle set on an empty freshly created Gradle/Groovy project on IntellJ. I use projectDir here in two places: in task definition and in task class definition. IntelliJ shows me the first use as incorrect - cannot resolve symbol. And it sees the second use as a correct one.
group 'test'
version '1.0-SNAPSHOT'
apply plugin: 'java'
apply plugin: 'groovy'
sourceCompatibility = 1.8
repositories {
mavenCentral()
}
dependencies {
compile 'org.codehaus.groovy:groovy-all:2.3.11'
testCompile group: 'junit', name: 'junit', version: '4.12'
}
task ProjectDirTest(type: ProjectDirTestClass){
println " -------------- $projectDir from task"
}
class ProjectDirTestClass extends DefaultTask {
#TaskAction
def greet() {
println " -------------- $projectDir from class"
}
}
configure(ProjectDirTest) {
group = 'ProjectDirTest'
description = 'ProjectDirTest'
}
But if I run the task, the first println works OK, with correct output:
12:55:41: Executing external task 'ProjectDirTest'...
-------------- C:\Users\543829657\testWorkspace from task
:ProjectDirTest FAILED
FAILURE: Build failed with an exception.
* Where:
Build file 'C:\Users\543829657\testWorkspace\build.gradle' line: 28
* What went wrong:
Execution failed for task ':ProjectDirTest'.
> Could not get unknown property 'projectDir' for task ':ProjectDirTest' of type ProjectDirTestClass.
But, as you see, at the second println there is a problem - Gradle does not see the projectDir variable.
I am already accustomed to incorrect IntelliJ marking errors. But how can I make the task class to see the the projectDir variable in runtime?
In the real task class I also cannot use the exec() command - Gradle does not see it, too.

Answer 1

I have found a temporary solution, to pass the project variable into the class and call all project variables with it:
task ProjectDirTest(type: ProjectDirTestClass){
println " -------------- $projectDir from task"
projectLoc = project
}
class ProjectDirTestClass extends DefaultTask {
Project projectLoc
#TaskAction
def greet() {
println " -------------- ${projectLoc.projectDir} from class"
}
}
The negative side is that I have to pass the same project for every task using that task class. It is not a good style.