Fixed error handling when Java version can't be determined (#118)

* Fixed error handling when Java version can't be determined

* Made build getJavaExecutableVersion more resilient to output variations

gradle/java.gradle

@@ -234,15 +234,20 @@ JavaVersion getJavaExecutableVersion(String path) {
       commandLine = [path, "-version"]
       errorOutput = stream
     }
-    def matcher = stream.toString() =~ /^(?:java|openjdk) version "([^"]+)"/
+    def output = stream.toString()
+    for (def line : output.split('\n')) {
+      line = line.trim()
+      def matcher = line =~ /^(?:java|openjdk) version "([^"]+)"/
       if (matcher) {
         def version = JavaVersion.toVersion(matcher.group(1))
         cache.put(path, version)
         return version
-    } else {
-      throw new GradleScriptException("Cannot determine java version: ${stream.toString}")
       }
     }
+
+    // Getting here means we didn't find a line matching the version pattern.
+    throw new GradleScriptException("Cannot determine java version. Executable: ${path}, output: ${output}", null)
+  }
 }
 
 ext {