Add project key to cache key (jenkinsci#837)

If a requests is sent with a project key, and the key is not part of the cache key, following requests for other projects will result in the cached repositories for the first project, leading to wrong results

src/main/java/com/cloudbees/jenkins/plugins/bitbucket/client/BitbucketCloudApiClient.java

@@ -787,11 +787,17 @@ public List<BitbucketCloudRepository> getRepositories(@CheckForNull UserRoleInRe
                 .set("pagelen", MAX_PAGE_LENGTH);
         if (StringUtils.isNotBlank(projectKey)) {
             template.set("q", "project.key=" + "\"" + projectKey + "\""); // q=project.key="<projectKey>"
+            cacheKey.append("::").append(projectKey);
+        } else {
+            cacheKey.append("::<undefined>");
         }
         if (role != null &&  authenticator != null) {
             template.set("role", role.getId());
             cacheKey.append("::").append(role.getId());
+        } else {
+            cacheKey.append("::<undefined>");
         }
+
         Callable<List<BitbucketCloudRepository>> request = () -> {
             List<BitbucketCloudRepository> repositories = new ArrayList<>();
             Integer pageNumber = 1;