eliminate shadow JAR (was causing build failures)

shadow jars defy intended Java design and are essentially obsolete
instead set up Gradle to run application with the JARs on the classpath
will require changing end-to-end/UI testing to use 'gradle runBackend'

.github/workflows/gradle.yml

@@ -42,10 +42,11 @@ jobs:
       run: gradle -q printVersion | head -n1
     - name: Build and test
       run: gradle build
-    - name: Ensure shadow JAR is runnable as local backend
+    # Check that build product is able to start up as a backend server before handing it to end-to-end testing
+    - name: Ensure backend runnable
       run: |
         cp analysis.properties.template analysis.properties
-        gradle testShadowJarRunnable
+        gradle testRunnable -x test
     - name: Publish to GH Packages
       # Supply access token to build.gradle (used in publishing.repositories.maven.credentials)
       env:

build.gradle

@@ -1,6 +1,6 @@
 plugins {
     id 'java'
-    id 'com.github.johnrengelman.shadow' version '6.0.0'
+    id 'application'
     id 'maven-publish'
     id 'com.palantir.git-version' version '0.12.3'
 }
@@ -13,8 +13,6 @@ java {
     toolchain {
         languageVersion.set(JavaLanguageVersion.of(19))
     }
-    // sourceCompatibility = JavaVersion.VERSION_19
-    // targetCompatibility = JavaVersion.VERSION_19
 }
 
 jar {
@@ -33,10 +31,6 @@ jar {
     }
 }
 
-shadowJar {
-    mergeServiceFiles()
-}
-
 // Allow reflective access by Kryo to normally closed Java internals.
 // This is used for testing equality, but also for building automatic Kryo (de)serializers.
 test {
@@ -81,19 +75,24 @@ task copyDependencies(type: Copy) {
     into 'dependencies'
 }
 
+application {
+    applicationDefaultJvmArgs = ['-Xmx4G']
+    mainClass = 'com.conveyal.analysis.BackendMain'
+}
+
 // Run R5 as a local analysis backend with all dependencies on the classpath, without building a shadowJar.
 task runBackend (type: JavaExec) {
-   dependsOn(build)
-   classpath(sourceSets.main.runtimeClasspath)
-   main("com.conveyal.analysis.BackendMain")
+    dependsOn(build)
+    classpath(sourceSets.main.runtimeClasspath)
+    main("com.conveyal.analysis.BackendMain")
 }
 
-// Start up an analysis local backend from a shaded JAR and ask it to shut down immediately.
-// This is used to check in the automated build that the JAR is usable before we keep it.
+// Start up an analysis local backend and ask it to shut down immediately.
+// This is used to check in the automated build that the JAR is usable in end-to-end tests before we keep it.
 // Create a configuration properties file (by copying the template) before running this task.
-task testShadowJarRunnable(type: JavaExec) {
-    dependsOn(shadowJar)
-    classpath(shadowJar.archiveFile.get())
+task testRunnable(type: JavaExec) {
+    dependsOn(build)
+    classpath(sourceSets.main.runtimeClasspath)
     main("com.conveyal.analysis.BackendMain")
     jvmArgs("-Dconveyal.immediate.shutdown=true")
 }