Appease pmd

Can be run via `gradle pmd`.

Mostly making fields final where appropriate.

app/src/main/java/org/fdroid/fdroid/views/AppDetailsRecyclerViewAdapter.java

@@ -752,28 +752,28 @@ public class AppDetailsRecyclerViewAdapter
         }
     }
 
-    private View.OnClickListener mOnInstallClickListener = new View.OnClickListener() {
+    private final View.OnClickListener mOnInstallClickListener = new View.OnClickListener() {
         @Override
         public void onClick(View v) {
             mCallbacks.installApk();
         }
     };
 
-    private View.OnClickListener mOnUnInstallClickListener = new View.OnClickListener() {
+    private final View.OnClickListener mOnUnInstallClickListener = new View.OnClickListener() {
         @Override
         public void onClick(View v) {
             mCallbacks.uninstallApk();
         }
     };
 
-    private View.OnClickListener mOnUpgradeClickListener = new View.OnClickListener() {
+    private final View.OnClickListener mOnUpgradeClickListener = new View.OnClickListener() {
         @Override
         public void onClick(View v) {
             mCallbacks.upgradeApk();
         }
     };
 
-    private View.OnClickListener mOnLaunchClickListener = new View.OnClickListener() {
+    private final View.OnClickListener mOnLaunchClickListener = new View.OnClickListener() {
         @Override
         public void onClick(View v) {
             mCallbacks.launchApk();

app/src/main/java/org/fdroid/fdroid/views/LinearLayoutManagerSnapHelper.java

@@ -21,8 +21,8 @@ public class LinearLayoutManagerSnapHelper extends LinearSnapHelper {
         void onSnappedToView(View view, int position);
     }
 
-    private LinearLayoutManager mLlm;
-    private OrientationHelper mOrientationHelper;
+    private final LinearLayoutManager mLlm;
+    private final OrientationHelper mOrientationHelper;
     private LinearSnapHelperListener mListener;
 
     public LinearLayoutManagerSnapHelper(LinearLayoutManager llm) {

app/src/main/java/org/fdroid/fdroid/views/ShareChooserDialog.java

@@ -52,10 +52,6 @@ public class ShareChooserDialog extends BottomSheetDialogFragment {
 
     private ShareChooserDialogListener mListener;
 
-    public ShareChooserDialog() {
-        super();
-    }
-
     private void setListener(ShareChooserDialogListener listener) {
         mListener = listener;
     }