Add helpful error messages/instructions for updating THIRD_PARTY_NOTICES.

PiperOrigin-RevId: 704353891

Author: gkdn

license_check/third_party_license_test.sh

@@ -2,6 +2,16 @@
 
 set -e
 
-python3 -m pip install requests
+if ! python3 -c "import requests"; then
+  if python3 -m pip --version; then
+    echo Installing \"requests\" package.
+    python3 -m pip install requests
+  else
+    echo Error: \"requests\" package is not available. \
+      Cannot install automatically since \"pip\" is also not available.
+    echo Please manually install \"requests\" or \"pip\" package.
+    exit 1
+  fi
+fi
 
 python3 license_check/third_party_license_test.py ${@}

maven_artifacts.bzl

@@ -17,6 +17,9 @@ MAVEN_ARTIFACTS = [
     "org.jspecify:jspecify:0.3.0",
 ]
 
+# After updating dependencies, please run the license check script from this directory:
+#   ./license_check/third_party_license_test.sh --update
+#
 # Note the added "@" after version tag to make easier to extract the root url
 ORDERED_POM_OR_GRADLE_FILE_LIST = [
     "https://github.com/kohsuke/args4j/blob/args4j-site-2.33@/args4j/pom.xml",