Resource leak when installing features through Gradle on Windows

[ericglau]

Describe the bug
After installing features through Gradle, the Liberty directory cannot be deleted. It looks like this is caused by InstallMap.java using a URLClassLoader with the Liberty jars, and the URLClassLoader is never closed. See this part of the code

open-liberty/dev/com.ibm.ws.install.map/src/com/ibm/ws/install/map/InstallMap.java

Line 543 in b06d50f

ClassLoader loader = new URLClassLoader(jars, getClass().getClassLoader());

Steps to Reproduce

1. Clone the gradle branch of https://github.com/OpenLiberty/demo-devmode
2. Run gradle installFeature
3. Run gradle clean

The following error occurs:

Execution failed for task ':clean'.
> java.io.IOException: Unable to delete directory 'C:\Users\Eric\git\demo-devmode\build'
    Failed to delete some children. This might happen because a process has files open or has its working directory set in the target directory.
    - C:\Users\Eric\git\demo-devmode\build\wlp\dev\api\spec\com.ibm.websphere.javaee.jsonp.1.0_1.0.35.jar
    - C:\Users\Eric\git\demo-devmode\build\wlp\dev\api\spec
    - C:\Users\Eric\git\demo-devmode\build\wlp\dev\api
    - C:\Users\Eric\git\demo-devmode\build\wlp\dev
    - C:\Users\Eric\git\demo-devmode\build\wlp\lib\com.ibm.ws.config_1.0.35.jar
    - C:\Users\Eric\git\demo-devmode\build\wlp\lib\com.ibm.ws.crypto.passwordutil_1.0.35.jar
    - C:\Users\Eric\git\demo-devmode\build\wlp\lib\com.ibm.ws.install.map_1.0.35.jar
    - C:\Users\Eric\git\demo-devmode\build\wlp\lib\com.ibm.ws.install_1.0.35.jar
    - C:\Users\Eric\git\demo-devmode\build\wlp\lib\com.ibm.ws.kernel.boot_1.0.35.jar
    - C:\Users\Eric\git\demo-devmode\build\wlp\lib\com.ibm.ws.kernel.feature_1.0.35.jar
    - C:\Users\Eric\git\demo-devmode\build\wlp\lib\com.ibm.ws.kernel.service_1.3.35.jar
    - C:\Users\Eric\git\demo-devmode\build\wlp\lib\com.ibm.ws.logging_1.0.35.jar
    - C:\Users\Eric\git\demo-devmode\build\wlp\lib\com.ibm.ws.org.apache.aries.util_1.0.35.jar
    - C:\Users\Eric\git\demo-devmode\build\wlp\lib\com.ibm.ws.org.eclipse.equinox.metatype_1.0.35.jar
    - C:\Users\Eric\git\demo-devmode\build\wlp\lib\com.ibm.ws.org.glassfish.json.1.0_1.0.35.jar
    - C:\Users\Eric\git\demo-devmode\build\wlp\lib\com.ibm.ws.product.utility_1.0.35.jar
    - and more ...
    New files were found. This might happen because a process is still writing to the target directory.
    - C:\Users\Eric\git\demo-devmode\build\wlp
    - C:\Users\Eric\git\demo-devmode\build\wlp\lib

Expected behavior
The Liberty directory should be able to be deleted.

Diagnostic information:

• OpenLiberty Version: any (tried 19.0.0.6, 19.0.0.9, 19.0.0.12).
• Java Version:

openjdk version "1.8.0_232"
OpenJDK Runtime Environment (AdoptOpenJDK)(build 1.8.0_232-b09)
OpenJDK 64-Bit Server VM (AdoptOpenJDK)(build 25.232-b09, mixed mode)

Additional context
The symptoms above happen only with Gradle on Windows.