#vulnerable code 
                                @Override
    public void execute() throws MojoExecutionException, MojoFailureException {
        try {
            // set git flow configuration
            initGitFlowConfig();

            // check uncommitted changes
            checkUncommittedChanges();

            // check snapshots dependencies
            if (!allowSnapshots) {
                checkSnapshotDependencies();
            }

            // fetch and check remote
            if (fetchRemote) {
                if (notSameProdDevName()) {
                    gitFetchRemoteAndCompare(gitFlowConfig
                            .getDevelopmentBranch());
                }
                gitFetchRemoteAndCompare(gitFlowConfig.getProductionBranch());
            }

            // git for-each-ref --count=1 refs/heads/release/*
            final String releaseBranch = gitFindBranches(
                    gitFlowConfig.getReleaseBranchPrefix(), true);

            if (StringUtils.isNotBlank(releaseBranch)) {
                throw new MojoFailureException(
                        "Release branch already exists. Cannot start release.");
            }

            // need to be in develop to get correct project version
            // git checkout develop
            gitCheckout(gitFlowConfig.getDevelopmentBranch());

            if (!skipTestProject) {
                // mvn clean test
                mvnCleanTest();
            }

            // get current project version from pom
            final String currentVersion = getCurrentProjectVersion();

            String defaultVersion = null;
            if (tychoBuild) {
                defaultVersion = currentVersion;
            } else {
                // get default release version
                try {
                    final DefaultVersionInfo versionInfo = new DefaultVersionInfo(
                            currentVersion);
                    defaultVersion = versionInfo.getReleaseVersionString();
                } catch (VersionParseException e) {
                    if (getLog().isDebugEnabled()) {
                        getLog().debug(e);
                    }
                }
            }

            if (defaultVersion == null) {
                throw new MojoFailureException(
                        "Cannot get default project version.");
            }

            String version = null;
            if (settings.isInteractiveMode()) {
                try {
                    version = prompter.prompt("What is release version? ["
                            + defaultVersion + "]");
                } catch (PrompterException e) {
                    getLog().error(e);
                }
            }

            if (StringUtils.isBlank(version)) {
                version = defaultVersion;
            }

            // execute if version changed
            if (!version.equals(currentVersion)) {
                // mvn set version
                mvnSetVersions(version);

                // git commit -a -m updating versions for release
                gitCommit(commitMessages.getReleaseStartMessage());
            }

            if (notSameProdDevName()) {
                // git checkout master
                gitCheckout(gitFlowConfig.getProductionBranch());

                gitMerge(gitFlowConfig.getDevelopmentBranch(), releaseRebase,
                        releaseMergeNoFF);
            }

            if (!skipTag) {
                if (tychoBuild && ArtifactUtils.isSnapshot(version)) {
                    version = version.replace("-" + Artifact.SNAPSHOT_VERSION,
                            "");
                }

                // git tag -a ...
                gitTag(gitFlowConfig.getVersionTagPrefix() + version,
                        commitMessages.getTagReleaseMessage());
            }

            if (notSameProdDevName()) {
                // git checkout develop
                gitCheckout(gitFlowConfig.getDevelopmentBranch());
            }

            String nextSnapshotVersion = null;
            // get next snapshot version
            try {
                final DefaultVersionInfo versionInfo = new DefaultVersionInfo(
                        version);
                nextSnapshotVersion = versionInfo.getNextVersion()
                        .getSnapshotVersionString();
            } catch (VersionParseException e) {
                if (getLog().isDebugEnabled()) {
                    getLog().debug(e);
                }
            }

            if (StringUtils.isBlank(nextSnapshotVersion)) {
                throw new MojoFailureException(
                        "Next snapshot version is blank.");
            }

            // mvn set version
            mvnSetVersions(nextSnapshotVersion);

            // git commit -a -m updating for next development version
            gitCommit(commitMessages.getReleaseFinishMessage());

            if (installProject) {
                // mvn clean install
                mvnCleanInstall();
            }

            if (pushRemote) {
                gitPush(gitFlowConfig.getProductionBranch(), !skipTag);
                if (notSameProdDevName()) {
                    gitPush(gitFlowConfig.getDevelopmentBranch(), !skipTag);
                }
            }
        } catch (CommandLineException e) {
            getLog().error(e);
        }
    } 
                            #location 81 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Override
    public void execute() throws MojoExecutionException, MojoFailureException {
        try {
            // set git flow configuration
            initGitFlowConfig();

            // check uncommitted changes
            checkUncommittedChanges();

            // check snapshots dependencies
            if (!allowSnapshots) {
                checkSnapshotDependencies();
            }

            // fetch and check remote
            if (fetchRemote) {
                if (notSameProdDevName()) {
                    gitFetchRemoteAndCompare(gitFlowConfig
                            .getDevelopmentBranch());
                }
                gitFetchRemoteAndCompare(gitFlowConfig.getProductionBranch());
            }

            // git for-each-ref --count=1 refs/heads/release/*
            final String releaseBranch = gitFindBranches(
                    gitFlowConfig.getReleaseBranchPrefix(), true);

            if (StringUtils.isNotBlank(releaseBranch)) {
                throw new MojoFailureException(
                        "Release branch already exists. Cannot start release.");
            }

            // need to be in develop to get correct project version
            // git checkout develop
            gitCheckout(gitFlowConfig.getDevelopmentBranch());

            if (!skipTestProject) {
                // mvn clean test
                mvnCleanTest();
            }

            // get current project version from pom
            final String currentVersion = getCurrentProjectVersion();

            String defaultVersion = null;
            if (tychoBuild) {
                defaultVersion = currentVersion;
            } else {
                // get default release version
                try {
                    final DefaultVersionInfo versionInfo = new DefaultVersionInfo(
                            currentVersion);
                    defaultVersion = versionInfo.getReleaseVersionString();
                } catch (VersionParseException e) {
                    if (getLog().isDebugEnabled()) {
                        getLog().debug(e);
                    }
                }
            }

            if (defaultVersion == null) {
                throw new MojoFailureException(
                        "Cannot get default project version.");
            }

            String version = null;
            if (settings.isInteractiveMode()) {
                try {
                    version = prompter.prompt("What is release version? ["
                            + defaultVersion + "]");
                } catch (PrompterException e) {
                    getLog().error(e);
                }
            } else {
                version = releaseVersion;
            }

            if (StringUtils.isBlank(version)) {
                version = defaultVersion;
            }

            // execute if version changed
            if (!version.equals(currentVersion)) {
                // mvn set version
                mvnSetVersions(version);

                // git commit -a -m updating versions for release
                gitCommit(commitMessages.getReleaseStartMessage());
            }

            if (notSameProdDevName()) {
                // git checkout master
                gitCheckout(gitFlowConfig.getProductionBranch());

                gitMerge(gitFlowConfig.getDevelopmentBranch(), releaseRebase,
                        releaseMergeNoFF);
            }

            if (!skipTag) {
                if (tychoBuild && ArtifactUtils.isSnapshot(version)) {
                    version = version.replace("-" + Artifact.SNAPSHOT_VERSION,
                            "");
                }

                // git tag -a ...
                gitTag(gitFlowConfig.getVersionTagPrefix() + version,
                        commitMessages.getTagReleaseMessage());
            }

            if (notSameProdDevName()) {
                // git checkout develop
                gitCheckout(gitFlowConfig.getDevelopmentBranch());
            }

            String nextSnapshotVersion = null;
            // get next snapshot version
            try {
                final DefaultVersionInfo versionInfo = new DefaultVersionInfo(
                        version);
                nextSnapshotVersion = versionInfo.getNextVersion()
                        .getSnapshotVersionString();
            } catch (VersionParseException e) {
                if (getLog().isDebugEnabled()) {
                    getLog().debug(e);
                }
            }

            if (StringUtils.isBlank(nextSnapshotVersion)) {
                throw new MojoFailureException(
                        "Next snapshot version is blank.");
            }

            // mvn set version
            mvnSetVersions(nextSnapshotVersion);

            // git commit -a -m updating for next development version
            gitCommit(commitMessages.getReleaseFinishMessage());

            if (installProject) {
                // mvn clean install
                mvnCleanInstall();
            }

            if (pushRemote) {
                gitPush(gitFlowConfig.getProductionBranch(), !skipTag);
                if (notSameProdDevName()) {
                    gitPush(gitFlowConfig.getDevelopmentBranch(), !skipTag);
                }
            }
        } catch (CommandLineException e) {
            getLog().error(e);
        }
    }