Building Flex app using gradlefx(some issue record)

In Android development,now I used Android Studio for my IDE,so using gradle for building android must using gradle script.

In my another programing skill Flex,Most of programmers use ant for building script.Now I have a modern choice: gradlefx.

Below record is for what I encounter some issue:

1.Ambiguous method overloading for method java.io.File#. error

So I get starling sample code from starling website.In starling sample,they use gradefx for building process.So  when enter "gradle" command in the sample folder.

G:\starling-2.0\samples>gradle
Parallel execution is an incubating feature.
Defining custom 'build' task when using the standard Gradle lifecycle plugins ha
s been deprecated and is scheduled to be removed in Gradle 3.0

FAILURE: Build failed with an exception.

* What went wrong:
A problem occurred configuring project ':demo_mobile'.
> Ambiguous method overloading for method java.io.File#.
Cannot resolve which method to invoke for [null] due to overlapping prototypes b
etween:
        [class java.lang.String]
        [class java.net.URI]

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug
option to get more log output.

BUILD FAILED

Total time: 35.549 secs

This issue is cause of FLEX_HOME did not define.
When I define FLEX_HOME in system environment,the error won't happen again.