message: Fix append method
diff: @@ -321,7 +321,7 @@ def doBuildMacOs(String buildType) {
  archiveArtifacts("build-macos-${buildType}/*.tar.xz")
  stash includes:"build-macos-${buildType}/*.tar.xz", name:"macos-${buildType}"
  - cocoaStashes.append("macos-${buildType}")
  + cocoaStashes << "macos-${buildType}"
  } finally {
  collectCompilerWarnings('clang', true)
  }
  @@ -345,7 +345,7 @@ def doBuildAppleDevice(String sdk, String buildType) {
  }
  archiveArtifacts("build-${sdk}-${buildType}/*.tar.xz")
  stash includes:"build-${sdk}-${buildType}/*.tar.xz", name:"cocoa-${sdk}-${buildType}"
  - cocoaStashes.append("cocoa-${sdk}-${buildType}")
  + cocoaStashes << "cocoa-${sdk}-${buildType}"
  } finally {
  collectCompilerWarnings('clang', true)
  }
  