Print JAVA_HOME and PATH in the java format checker task (#997)

* Print JAVA_HOME and PATH in the java format checker task

This allows is to identify if the java version is incompatible with the
formater checker jar file.

* Show which Java binary is used

* show java version

* Fix exeInBash arguments

build.gradle

@@ -401,6 +401,10 @@ def createGetBuildSrcDirectDepsTask(outputFileName) {
 
 rootProject.ext {
   invokeJavaDiffFormatScript = { action ->
+    println("JAVA_HOME=${System.env.JAVA_HOME}")
+    println("PATH=${System.env.PATH}")
+    println(ext.execInBash("type java", "${rootDir}"))
+    println(ext.execInBash("java -version", "${rootDir}"))
     def scriptDir = rootDir.path.endsWith('buildSrc')
             ? "${rootDir}/../java-format"
             : "${rootDir}/java-format"