cosmetic: eliminate some code warnings
diff --git a/src/main/java/org/apache/sling/fsprovider/internal/mapper/ContentFileResourceMapper.java b/src/main/java/org/apache/sling/fsprovider/internal/mapper/ContentFileResourceMapper.java
index c69eb9e..d27458e 100644
--- a/src/main/java/org/apache/sling/fsprovider/internal/mapper/ContentFileResourceMapper.java
+++ b/src/main/java/org/apache/sling/fsprovider/internal/mapper/ContentFileResourceMapper.java
@@ -144,14 +144,4 @@
         return getFile(parentPath, nextSubPath);
     }
     
-    private boolean isNodeDescriptor(File file) {
-        for (String filenameSuffix : contentFileExtensions.getSuffixes()) {
-            if (StringUtils.endsWith(file.getPath(), filenameSuffix)) {
-                File fileWithoutSuffix = new File(StringUtils.substringBeforeLast(file.getPath(), filenameSuffix));
-                return fileStatCache.exists(fileWithoutSuffix);
-            }
-        }
-        return false;
-    }
-    
 }
diff --git a/src/main/java/org/apache/sling/fsprovider/internal/mapper/FileVaultResourceMapper.java b/src/main/java/org/apache/sling/fsprovider/internal/mapper/FileVaultResourceMapper.java
index 39186ea..41b2bdd 100644
--- a/src/main/java/org/apache/sling/fsprovider/internal/mapper/FileVaultResourceMapper.java
+++ b/src/main/java/org/apache/sling/fsprovider/internal/mapper/FileVaultResourceMapper.java
@@ -24,7 +24,6 @@
 import java.io.File;
 import java.io.IOException;
 import java.util.Arrays;
-import java.util.Comparator;
 import java.util.Iterator;
 import java.util.LinkedHashSet;
 import java.util.Map;
diff --git a/src/main/java/org/apache/sling/fsprovider/internal/mapper/LazyModifiedDateResourceMetadata.java b/src/main/java/org/apache/sling/fsprovider/internal/mapper/LazyModifiedDateResourceMetadata.java
index 54443e6..78d0088 100644
--- a/src/main/java/org/apache/sling/fsprovider/internal/mapper/LazyModifiedDateResourceMetadata.java
+++ b/src/main/java/org/apache/sling/fsprovider/internal/mapper/LazyModifiedDateResourceMetadata.java
@@ -18,14 +18,13 @@
  */
 package org.apache.sling.fsprovider.internal.mapper;
 
-import org.apache.sling.api.resource.ResourceMetadata;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.io.File;
 
-class LazyModifiedDateResourceMetadata extends ResourceMetadata {
+import org.apache.sling.api.resource.ResourceMetadata;
 
+class LazyModifiedDateResourceMetadata extends ResourceMetadata {
+    private static final long serialVersionUID = 1L;
+    
     private volatile long lastModified = -1;
     private File file;
 
diff --git a/src/test/java/org/apache/sling/fsprovider/internal/FileVaultContentTest.java b/src/test/java/org/apache/sling/fsprovider/internal/FileVaultContentTest.java
index 42a885d..40a1af8 100644
--- a/src/test/java/org/apache/sling/fsprovider/internal/FileVaultContentTest.java
+++ b/src/test/java/org/apache/sling/fsprovider/internal/FileVaultContentTest.java
@@ -27,16 +27,13 @@
 import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
 
-import java.util.ArrayList;
 import java.util.HashMap;
-import java.util.List;
 import java.util.Map;
 
 import javax.jcr.Node;
 import javax.jcr.RepositoryException;
 import javax.jcr.Session;
 
-import com.google.common.collect.Iterables;
 import org.apache.sling.api.resource.Resource;
 import org.apache.sling.api.resource.ValueMap;
 import org.apache.sling.fsprovider.internal.TestUtils.RegisterFsResourcePlugin;
@@ -48,11 +45,10 @@
 import org.junit.Rule;
 import org.junit.Test;
 
-import com.google.common.collect.ImmutableList;
-
 /**
  * Test access FileFault XML files, folders and content.
  */
+@SuppressWarnings("null")
 public class FileVaultContentTest {
 
     private Resource damAsset;
diff --git a/src/test/java/org/apache/sling/fsprovider/internal/FilesFolderTest.java b/src/test/java/org/apache/sling/fsprovider/internal/FilesFolderTest.java
index 3965583..18dffdb 100644
--- a/src/test/java/org/apache/sling/fsprovider/internal/FilesFolderTest.java
+++ b/src/test/java/org/apache/sling/fsprovider/internal/FilesFolderTest.java
@@ -38,6 +38,7 @@
 /**
  * Test access to files and folders from file system.
  */
+@SuppressWarnings("null")
 public class FilesFolderTest {
 
     private Resource root;
diff --git a/src/test/java/org/apache/sling/fsprovider/internal/JcrMixedTest.java b/src/test/java/org/apache/sling/fsprovider/internal/JcrMixedTest.java
index b3e4d3b..5646c78 100644
--- a/src/test/java/org/apache/sling/fsprovider/internal/JcrMixedTest.java
+++ b/src/test/java/org/apache/sling/fsprovider/internal/JcrMixedTest.java
@@ -38,6 +38,7 @@
 /**
  * Test access mixed with JCR content on same path.
  */
+@SuppressWarnings("null")
 public class JcrMixedTest {
 
     private Resource root;
diff --git a/src/test/java/org/apache/sling/fsprovider/internal/JcrXmlContentTest.java b/src/test/java/org/apache/sling/fsprovider/internal/JcrXmlContentTest.java
index 59c20d7..2bca0eb 100644
--- a/src/test/java/org/apache/sling/fsprovider/internal/JcrXmlContentTest.java
+++ b/src/test/java/org/apache/sling/fsprovider/internal/JcrXmlContentTest.java
@@ -49,6 +49,7 @@
 /**
  * Test access to files and folders from file system.
  */
+@SuppressWarnings("null")
 public class JcrXmlContentTest {
 
     private Resource root;
diff --git a/src/test/java/org/apache/sling/fsprovider/internal/JsonContentTest.java b/src/test/java/org/apache/sling/fsprovider/internal/JsonContentTest.java
index 21df79a..9d953f5 100644
--- a/src/test/java/org/apache/sling/fsprovider/internal/JsonContentTest.java
+++ b/src/test/java/org/apache/sling/fsprovider/internal/JsonContentTest.java
@@ -62,6 +62,7 @@
 /**
  * Test access to files and folders and JSON content from file system.
  */
+@SuppressWarnings("null")
 public class JsonContentTest {
 
     private Resource root;
diff --git a/src/test/java/org/apache/sling/fsprovider/internal/TestUtils.java b/src/test/java/org/apache/sling/fsprovider/internal/TestUtils.java
index ffa5934..4b9e300 100644
--- a/src/test/java/org/apache/sling/fsprovider/internal/TestUtils.java
+++ b/src/test/java/org/apache/sling/fsprovider/internal/TestUtils.java
@@ -47,6 +47,7 @@
 import org.apache.sling.testing.mock.sling.context.SlingContextImpl;
 import org.jetbrains.annotations.NotNull;
 
+@SuppressWarnings("null")
 class TestUtils {
 
     public static class RegisterFsResourcePlugin extends AbstractContextPlugin<SlingContextImpl> {