#vulnerable code 
                                public void check(GitlabMergeRequest gitlabMergeRequest) {

        if (mergeRequestStatus == null) {
            mergeRequestStatus = new GitlabMergeRequestStatus();
        }

        if (iid == null) {
            iid = gitlabMergeRequest.getIid();
        }

        if (targetBranch == null || targetBranch.trim().isEmpty()) {
            targetBranch = gitlabMergeRequest.getTargetBranch();
        }

        if (sourceBranch == null || sourceBranch.trim().isEmpty()) {
            sourceBranch = gitlabMergeRequest.getSourceBranch();
        }

        if (description == null || description.trim().isEmpty()) {
            description = gitlabMergeRequest.getDescription();
            
            if (description == null) { description = ""; }
        }

        if (sourceProject == null || sourceProject.getId() == null || sourceProject.getName() == null) {
            try {
                GitlabAPI api = builder.getGitlab().get();
                sourceProject = getSourceProject(gitlabMergeRequest, api);
            } catch (IOException e) {
                LOGGER.log(Level.SEVERE, "Failed to get source project for Merge request " + gitlabMergeRequest.getId() + " :\n" + e.getMessage());
                return;
            }
        }
        
        try {
            GitlabAPI api = builder.getGitlab().get();
            GitlabCommit latestCommit = getLatestCommit(gitlabMergeRequest, api);
            
            Map<String, String> customParameters = getSpecifiedCustomParameters(gitlabMergeRequest, api);
            build(customParameters, latestCommit.getId(), gitlabMergeRequest);
        } catch (IOException e) {
            LOGGER.log(Level.SEVERE, "Failed to fetch commits for Merge Request " + gitlabMergeRequest.getId());
        }
    } 
                            #location 40 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public void check(GitlabMergeRequest gitlabMergeRequest) {

        if (mergeRequestStatus == null) {
            mergeRequestStatus = new GitlabMergeRequestStatus();
        }

        if (iid == null) {
            iid = gitlabMergeRequest.getIid();
        }

        if (targetBranch == null || targetBranch.trim().isEmpty()) {
            targetBranch = gitlabMergeRequest.getTargetBranch();
        }

        if (sourceBranch == null || sourceBranch.trim().isEmpty()) {
            sourceBranch = gitlabMergeRequest.getSourceBranch();
        }

        if (description == null || description.trim().isEmpty()) {
            description = gitlabMergeRequest.getDescription();
            
            if (description == null) { description = ""; }
        }

        if (sourceProject == null || sourceProject.getId() == null || sourceProject.getName() == null) {
            try {
                GitlabAPI api = builder.getGitlab().get();
                sourceProject = getSourceProject(gitlabMergeRequest, api);
            } catch (IOException e) {
                LOGGER.log(Level.SEVERE, "Failed to get source project for Merge request " + gitlabMergeRequest.getId() + " :\n" + e.getMessage());
                return;
            }
        }
        
        try {
            GitlabAPI api = builder.getGitlab().get();
            GitlabCommit latestCommit = getLatestCommit(gitlabMergeRequest, api);

            if (latestCommit == null) { // the source branch has been removed
                return;
            }
            
            Map<String, String> customParameters = getSpecifiedCustomParameters(gitlabMergeRequest, api);
            build(customParameters, latestCommit.getId(), gitlabMergeRequest);
        } catch (IOException e) {
            LOGGER.log(Level.SEVERE, "Failed to fetch commits for Merge Request " + gitlabMergeRequest.getId());
        }
    }