chore: Fix CI issue

Author: lqiu96

.github/workflows/downstream.yaml

@@ -63,4 +63,4 @@ jobs:
           sudo apt-get update
           sudo apt-get -y install libxml2-utils
       - name: Perform downstream compatibility testing
-        run: ./.kokoro/presubmit/downstream-compatibility-spring.sh
+        run: ./.kokoro/presubmit/downstream-compatibility-spring.sh

.github/workflows/downstream_protobuf_source_compatibility_check_nightly.yaml

@@ -1,14 +1,11 @@
 on:
-  push:
-    branches:
-      - main
   workflow_dispatch:
     inputs:
       protobuf_versions:
-        description: 'Comma separated list of Protobuf-Java versions (i.e. 3.25.5, 4.28.3)'
+        description: 'Comma separated list of Protobuf-Java versions (i.e. "3.25.5","4.28.3")'
+        # Default value for workflow_dispatch flow. If updating default value, update below as well.
         default: '"3.25.5","4.28.3"'
-        required: false
-  pull_request:
+        required: true
   schedule:
     - cron: '0 1 * * *' # Nightly at 1am
 
@@ -35,9 +32,8 @@ jobs:
           - java-storage
           - java-storage-nio
         # Specify the Protobuf versions here as well because the default values above are only supplied from
-        # workflow_dispatch flow. The nightly workflow doesn't have a default input otherwise. The default
-        # values above provide an example of the expected format in the UI. When updating, update both sections
-        # to provide a proper default.
+        # the workflow_dispatch flow. Without this, the nightly workflow doesn't have a default input otherwise
+        # and would resolve to ''. When updating, update both places to keep default values consistent.
         protobuf-version: ${{ fromJSON(format('[{0}]', inputs.protobuf_versions || '"3.25.5","4.28.3"')) }}
     steps:
       - uses: actions/checkout@v3
@@ -46,9 +42,5 @@ jobs:
           java-version: 17
           distribution: temurin
       - run: mvn -version
-      - name: Install xmllint
-        run: |
-          sudo apt-get update
-          sudo apt-get -y install libxml2-utils
       - name: Perform downstream compatibility testing
         run: REPOS_UNDER_TEST="${{ matrix.repo }}" PROTOBUF_RUNTIME_VERSION="${{ matrix.protobuf-version}}" ./.kokoro/presubmit/downstream-protobuf-source-compatibility.sh

.kokoro/presubmit/downstream-protobuf-source-compatibility.sh

@@ -27,10 +27,7 @@ if [ -z "${PROTOBUF_RUNTIME_VERSION}" ]; then
   exit 1
 fi
 
-# Get the directory of the build script
-scriptDir=$(realpath "$(dirname "${BASH_SOURCE[0]}")")
 cd "${scriptDir}/../.." # cd to the root of this repo
-source "$scriptDir/common.sh"
 
 setup_maven_mirror