Address more sonar issues in drools-pdp

Addressed the following sonar issues:
- use of "synchronized"
- use Files.delete() instead of File.delete()

Issue-ID: POLICY-2305
Change-Id: Id55628fe12d9d764616e57321382a70cb5704ba1
Signed-off-by: Jim Hahn <jrh3@att.com>
diff --git a/feature-state-management/src/main/java/org/onap/policy/drools/statemanagement/RepositoryAudit.java b/feature-state-management/src/main/java/org/onap/policy/drools/statemanagement/RepositoryAudit.java
index bf6b2e7..8f33f92 100644
--- a/feature-state-management/src/main/java/org/onap/policy/drools/statemanagement/RepositoryAudit.java
+++ b/feature-state-management/src/main/java/org/onap/policy/drools/statemanagement/RepositoryAudit.java
@@ -522,19 +522,26 @@
     private final class RecursivelyDeleteDirectory extends SimpleFileVisitor<Path> {
         @Override
         public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
-            file.toFile().delete();
-            return FileVisitResult.CONTINUE;
+            return deletePath("file", file);
         }
 
         @Override
         public FileVisitResult postVisitDirectory(Path file, IOException ex) throws IOException {
             if (ex == null) {
-                file.toFile().delete();
-                return FileVisitResult.CONTINUE;
+                return deletePath("directory", file);
             } else {
                 throw ex;
             }
         }
+
+        private FileVisitResult deletePath(String type, Path file) {
+            try {
+                Files.delete(file);
+            } catch (IOException e) {
+                logger.warn("failed to delete {} {}", type, file, e);
+            }
+            return FileVisitResult.CONTINUE;
+        }
     }
 
     /* ============================================================ */
diff --git a/policy-core/src/main/java/org/onap/policy/drools/core/lock/LockImpl.java b/policy-core/src/main/java/org/onap/policy/drools/core/lock/LockImpl.java
index 9596dbe..8866eb8 100644
--- a/policy-core/src/main/java/org/onap/policy/drools/core/lock/LockImpl.java
+++ b/policy-core/src/main/java/org/onap/policy/drools/core/lock/LockImpl.java
@@ -100,13 +100,15 @@
      * This method always succeeds, unless the lock is already unavailable.
      */
     @Override
-    public synchronized boolean free() {
-        if (isUnavailable()) {
-            return false;
-        }
+    public boolean free() {
+        synchronized (this) {
+            if (isUnavailable()) {
+                return false;
+            }
 
-        logger.info("releasing lock: {}", this);
-        setState(LockState.UNAVAILABLE);
+            logger.info("releasing lock: {}", this);
+            setState(LockState.UNAVAILABLE);
+        }
 
         return true;
     }
diff --git a/policy-management/src/main/java/org/onap/policy/drools/system/internal/FeatureLockImpl.java b/policy-management/src/main/java/org/onap/policy/drools/system/internal/FeatureLockImpl.java
index 6b0c8a4..799cca7 100644
--- a/policy-management/src/main/java/org/onap/policy/drools/system/internal/FeatureLockImpl.java
+++ b/policy-management/src/main/java/org/onap/policy/drools/system/internal/FeatureLockImpl.java
@@ -119,7 +119,7 @@
      * @return {@code true} if the lock can be freed, {@code false} if the lock is
      *         unavailable
      */
-    protected boolean freeAllowed() {
+    protected synchronized boolean freeAllowed() {
         // do a quick check of the state
         if (isUnavailable()) {
             return false;
@@ -150,7 +150,7 @@
      * @return {@code true} if the lock can be extended, {@code false} if the lock is
      *         unavailable
      */
-    protected boolean extendAllowed(int holdSec, LockCallback callback) {
+    protected synchronized boolean extendAllowed(int holdSec, LockCallback callback) {
         if (holdSec < 0) {
             throw new IllegalArgumentException("holdSec is negative");
         }
diff --git a/policy-management/src/main/java/org/onap/policy/drools/system/internal/SimpleLockManager.java b/policy-management/src/main/java/org/onap/policy/drools/system/internal/SimpleLockManager.java
index 1df139e..c2c921f 100644
--- a/policy-management/src/main/java/org/onap/policy/drools/system/internal/SimpleLockManager.java
+++ b/policy-management/src/main/java/org/onap/policy/drools/system/internal/SimpleLockManager.java
@@ -227,7 +227,7 @@
         }
 
         @Override
-        public synchronized boolean free() {
+        public boolean free() {
             if (!freeAllowed()) {
                 return false;
             }