Fix ProtectedMembersInFinalClass error flagged by error prone

Running recent error prone version complaining on that code:

DeleteCommand.java:53: error: [ProtectedMembersInFinalClass] Make members
of final classes package-private: <init>
  protected DeleteCommand(DeleteProject deleteProject, DeletePreconditions preConditions) {
            ^
    (see https://errorprone.info/bugpattern/ProtectedMembersInFinalClass)

Bug: Issue 12677
Change-Id: I3ef90ac3106240403dc88178262edf2447f30cb8
diff --git a/src/main/java/com/googlesource/gerrit/plugins/deleteproject/DeleteCommand.java b/src/main/java/com/googlesource/gerrit/plugins/deleteproject/DeleteCommand.java
index e5df5a3..a444859 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/deleteproject/DeleteCommand.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/deleteproject/DeleteCommand.java
@@ -25,7 +25,7 @@
 import org.kohsuke.args4j.Option;
 
 @CommandMetaData(name = "delete", description = "Delete specific project")
-public final class DeleteCommand extends SshCommand {
+final class DeleteCommand extends SshCommand {
   private static final String FORCE_DELETE =
       "%s - To really delete '%s', re-run with the --force flag.";
   private static final String REALLY_DELETE =
@@ -50,7 +50,7 @@
   private final DeletePreconditions preConditions;
 
   @Inject
-  protected DeleteCommand(DeleteProject deleteProject, DeletePreconditions preConditions) {
+  DeleteCommand(DeleteProject deleteProject, DeletePreconditions preConditions) {
     this.deleteProject = deleteProject;
     this.preConditions = preConditions;
   }