@Override
    public GitRepoResponse pullFromGit(final GitRepoDoc gitRepoDoc) {
        Objects.requireNonNull(gitRepoDoc);
        GitRepoResponse response;
        try {
            LOGGER.info("Pulling from Git repo: {}", gitRepoDoc.getUrl());
            List<Message> messages = gitRepoStorageServiceProvider.get()
                    .importDoc(gitRepoDoc);
            response = this.createResponse(messages);
        } catch (Exception e) {
            response = new GitRepoResponse(false, e.getMessage());
        }
        return response;
    }
Called on the server when a REST request is received from the
UI for a Git Pull.
@param gitRepoDoc The doc holding git repo info.
@return a GitRepoRespose with all the messages about
whether it worked.
stroom-gitrepo/stroom-gitrepo-impl/src/main/java/stroom/gitrepo/impl/GitRepoResourceImpl.java