Added Gradle dependency lock support.

Applied changes requested by review (@JLLeitschuh).

.gitignore

@@ -19,6 +19,9 @@ gradle-app.setting
 # Avoid ignoring Gradle wrapper jar file (.jar files are usually ignored)
 !gradle-wrapper.jar
 
+#Gradle-Lock files in _ext just serving as an input for lib-extra
+_ext/*/gradle/dependency-locks/compileClasspath.lockfile
+
 ### Eclipse ###
 *.pydevproject
 .metadata

_ext/eclipse-base/src/main/java/com/diffplug/spotless/extra/eclipse/base/osgi/ResourceAccessor.java

@@ -77,7 +77,7 @@ private static BundleFile getBundlFile(Class<?> clazz) throws BundleException {
 		try {
 			return jarOrDirectory.isDirectory() ? new DirBundleFile(jarOrDirectory, false) : new ZipBundleFile(jarOrDirectory, null, null, null);
 		} catch (IOException e) {
-			throw new BundleException(String.format("Cannot access bundle at '%s'.", jarOrDirectory), BundleException.READ_ERROR);
+			throw new BundleException(String.format("Cannot access bundle at '%s'.", jarOrDirectory), BundleException.READ_ERROR, e);
 		}
 	}
 

_ext/gradle/java-setup.gradle

@@ -16,6 +16,18 @@ sourceCompatibility = ext_VER_JAVA
 targetCompatibility = ext_VER_JAVA
 tasks.withType(JavaCompile) { options.encoding = 'UTF-8' }
 
+// Use file locking
+configurations {
+    compileClasspath {
+        def gradleVersion = GradleVersion.current()
+        def requiredVersion = GradleVersion.version('4.8')
+        if (gradleVersion >= requiredVersion) {
+            resolutionStrategy.activateDependencyLocking()
+        }
+    }
+}
+
+
 /////////////
 // ECLIPSE //
 /////////////