Do not re-download java dependencies every time. (#26887)

* Do not re-download java dependencies every time.

This moves java dependency download time from 500ms to 5ms after
the initial download.

If we get more dependencies, the savings should be even better.

* Restyled by shellharden

* Restyled by shfmt

---------

Co-authored-by: Andrei Litvin <andreilitvin@google.com>
Co-authored-by: Restyled.io <commits@restyled.io>

third_party/java_deps/set_up_java_deps.sh

@@ -16,12 +16,26 @@
 #    limitations under the License.
 #
 
+set -e
+
 mkdir -p third_party/java_deps/artifacts
-curl --fail --location --silent --show-error https://repo1.maven.org/maven2/com/google/code/findbugs/jsr305/3.0.2/jsr305-3.0.2.jar -o third_party/java_deps/artifacts/jsr305-3.0.2.jar
-curl --fail --location --silent --show-error https://repo1.maven.org/maven2/org/json/json/20220924/json-20220924.jar -o third_party/java_deps/artifacts/json-20220924.jar
-curl --fail --location --silent --show-error https://repo1.maven.org/maven2/org/jetbrains/kotlin/kotlin-stdlib/1.8.10/kotlin-stdlib-1.8.10.jar -o third_party/java_deps/artifacts/kotlin-stdlib-1.8.10.jar
-curl --fail --location --silent --show-error https://repo1.maven.org/maven2/org/jetbrains/kotlin/kotlin-test/1.8.10/kotlin-test-1.8.10.jar -o third_party/java_deps/artifacts/kotlin-test-1.8.10.jar
-curl --fail --location --silent --show-error https://repo1.maven.org/maven2/com/google/protobuf/protobuf-java/3.22.0/protobuf-java-3.22.0.jar -o third_party/java_deps/artifacts/protobuf-java-3.22.0.jar
-curl --fail --location --silent --show-error https://repo1.maven.org/maven2/com/google/truth/truth/1.1.3/truth-1.1.3.jar -o third_party/java_deps/artifacts/truth-1.1.3.jar
-curl --fail --location --silent --show-error https://repo1.maven.org/maven2/junit/junit/4.13.2/junit-4.13.2.jar -o third_party/java_deps/artifacts/junit-4.13.2.jar
-curl --fail --location --silent --show-error https://repo1.maven.org/maven2/com/google/code/gson/gson/2.9.1/gson-2.9.1.jar -o third_party/java_deps/artifacts/gson-2.9.1.jar
+
+function download_maven_jar() {
+    _MAVEN_PATH=$1
+    _JAR_NAME=$2
+
+    if [ ! -f "third_party/java_deps/artifacts/$_JAR_NAME" ]; then
+        curl --fail --location --silent --show-error \
+            "https://repo1.maven.org/maven2/$_MAVEN_PATH/$_JAR_NAME" \
+            -o "third_party/java_deps/artifacts/$_JAR_NAME"
+    fi
+}
+
+download_maven_jar "com/google/code/findbugs/jsr305/3.0.2" "jsr305-3.0.2.jar"
+download_maven_jar "org/json/json/20220924" "json-20220924.jar"
+download_maven_jar "org/jetbrains/kotlin/kotlin-stdlib/1.8.10" "kotlin-stdlib-1.8.10.jar"
+download_maven_jar "org/jetbrains/kotlin/kotlin-test/1.8.10" "kotlin-test-1.8.10.jar"
+download_maven_jar "com/google/protobuf/protobuf-java/3.22.0" "protobuf-java-3.22.0.jar"
+download_maven_jar "com/google/truth/truth/1.1.3" "truth-1.1.3.jar"
+download_maven_jar "junit/junit/4.13.2" "junit-4.13.2.jar"
+download_maven_jar "com/google/code/gson/gson/2.9.1" "gson-2.9.1.jar"