Add public method to get no-op global lock

internal/zinc-ivy-integration/src/main/java/sbt/inc/ZincBridgeProvider.java

@@ -12,6 +12,7 @@ import xsbti.Logger;
 import xsbti.compile.CompilerBridgeProvider;
 
 import java.io.File;
+import java.util.concurrent.Callable;
 
 public final class ZincBridgeProvider {
     /**
@@ -46,6 +47,44 @@ public final class ZincBridgeProvider {
         return ZincComponentCompiler$.MODULE$.getDefaultConfiguration(baseDirectory, ivyHome, resolvers, logger);
     }
 
+    /**
+     * Cast a CheckedException as an unchecked one.
+     *
+     * @param throwable to cast
+     * @param <T>       the type of the Throwable
+     * @return this method will never return a Throwable instance, it will just throw it.
+     * @throws T the throwable as an unchecked throwable
+     */
+    @SuppressWarnings("unchecked")
+    private static <T extends Throwable> RuntimeException rethrow(Throwable throwable) throws T {
+        throw (T) throwable; // rely on vacuous cast
+    }
+
+
+    /**
+     * Defines a global lock that does nothing but calling the callable to synchronize
+     * across threads. The lock file is used to resolve and download dependencies via ivy.
+     * <p>
+     * This operation is necesary to invoke {@link ZincBridgeProvider#getProvider(File, GlobalLock, ComponentProvider, IvyConfiguration, Logger)}.
+     *
+     * @return A default global lock.
+     */
+    public static GlobalLock getDefaultLock() {
+        return new GlobalLock() {
+            @Override
+            public <T> T apply(File lockFile, Callable<T> run) {
+                T value = null;
+                try {
+                    value = run.call();
+                } catch (Exception e) {
+                    // Rethrow runtime exception because apply does not define throwing Exception
+                    rethrow(e);
+                }
+                return value;
+            }
+        };
+    }
+
     /**
      * Get a compiler bridge provider that allows the user to fetch Scala and a compiled bridge.
      *