message: Fix string manipulation
diff: @@ -208,18 +208,18 @@ def doBuildInDocker(String buildType, String sanitizeMode='', boolean enableAsse
  buildEnv = docker.build('realm-core-clang:snapshot', '-f clang.Dockerfile .')
  }
  def environment = environment()
  - def targetBuildType = new String(buildType)
  + def targetBuildType = "${buildType}"
  def cmakeFlags = ''
  if (sanitizeMode.contains('thread')) {
  cmakeFlags = '-D REALM_TSAN=ON'
  - targetBuildType += '+TSAN'
  + targetBuildType = '${targetBuildType}+TSAN'
  } else if (sanitizeMode.contains('address')) {
  cmakeFlags = '-D REALM_ASAN=ON'
  - targetBuildType += '+ASAN'
  + targetBuildType = '${targetBuildType}+ASAN'
  }
  if (enableAssertions) {
  cmakeFlags += ' -DREALM_ENABLE_ASSERTIONS=ON'
  - targetBuildType += '+Assertions'
  + targetBuildType = '${targetBuildType}+Assertions'
  }
  withEnv(environment) {
  buildEnv.inside(sanitizeMode == 'address' ? '--privileged' : '') {
  