Fix warnings, make relativePathResolver final

Author: Maple Buice

src/test/java/com/hubspot/jinjava/lib/tag/FromTagTest.java

@@ -26,7 +26,8 @@ public class FromTagTest extends BaseInterpretingTest {
   public void setup() {
     jinjava.setResourceLocator(
       new ResourceLocator() {
-        private RelativePathResolver relativePathResolver = new RelativePathResolver();
+        private final RelativePathResolver relativePathResolver =
+          new RelativePathResolver();
 
         @Override
         public String getString(

src/test/java/com/hubspot/jinjava/lib/tag/eager/EagerFromTagTest.java

@@ -28,7 +28,8 @@ public class EagerFromTagTest extends FromTagTest {
   public void eagerSetup() {
     jinjava.setResourceLocator(
       new ResourceLocator() {
-        private RelativePathResolver relativePathResolver = new RelativePathResolver();
+        private final RelativePathResolver relativePathResolver =
+          new RelativePathResolver();
 
         @Override
         public String getString(
@@ -128,7 +129,9 @@ public void itDefersImport() {}
   public void itResolvesNestedRelativeImportsInEagerMode() throws Exception {
     jinjava.setResourceLocator(
       new ResourceLocator() {
-        private RelativePathResolver relativePathResolver = new RelativePathResolver();
+        private final RelativePathResolver relativePathResolver =
+          new RelativePathResolver();
+
         private final java.util.Map<String, String> templates =
           new java.util.HashMap<>() {
             {