Deprecate BootJar#getConfigurations

Fixes gh-23527

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/bundling/BootJar.java

@@ -21,6 +21,7 @@ import java.util.Collections;
 import java.util.concurrent.Callable;
 
 import org.gradle.api.Action;
+import org.gradle.api.Project;
 import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.file.CopySpec;
 import org.gradle.api.file.FileCollection;
@@ -117,7 +118,14 @@ public class BootJar extends Jar implements BootArchive {
 		return this.support.createCopyAction(this);
 	}
 
+	/**
+	 * Returns the {@link Configuration Configurations} of the project associated with
+	 * this task.
+	 * @return the configurations
+	 * @deprecated since 2.3.5 in favor of {@link Project#getConfigurations}
+	 */
 	@Internal
+	@Deprecated
 	protected Iterable<Configuration> getConfigurations() {
 		return getProject().getConfigurations();
 	}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/tasks/bundling/BootJarTests.java

@@ -347,6 +347,7 @@ class BootJarTests extends AbstractBootArchiveTests<TestBootJar> {
 		private Iterable<Configuration> configurations = Collections.emptySet();
 
 		@Override
+		@SuppressWarnings("deprecation")
 		protected Iterable<Configuration> getConfigurations() {
 			return this.configurations;
 		}