Remove ProjectCache#checkedGet and move callers to #get

In an effort to make it impossible to use the ProjectCache interface the
wrong way, we are simplifying the interface to just a single option for
getting a project. The #get method throws a StorageException in case loading
failed and returns Optional#empty in case the project does not exist.

Change-Id: I7e3ecf2de3bc975d1c35ee8a848ac61def7af252

java/com/google/gerrit/server/permissions/DefaultPermissionBackend.java

@@ -15,6 +15,7 @@
 package com.google.gerrit.server.permissions;
 
 import static com.google.gerrit.server.permissions.DefaultPermissionMappings.globalPermissionName;
+import static com.google.gerrit.server.project.ProjectCache.illegalState;
 import static java.util.Objects.requireNonNull;
 import static java.util.stream.Collectors.toSet;
 
@@ -103,7 +104,7 @@ public class DefaultPermissionBackend extends PermissionBackend {
     @Override
     public ForProject project(Project.NameKey project) {
       try {
-        ProjectState state = projectCache.checkedGet(project);
+        ProjectState state = projectCache.get(project).orElseThrow(illegalState(project));
         ProjectControl control =
             PerThreadCache.getOrCompute(
                 PerThreadCache.Key.create(ProjectControl.class, project, user.getCacheKey()),