Refine workaround for JDK-8156584

The previous workaround worked but prevented caching of every test
task as the value of system property pointing to the custom security
properties file varied from build to build.

This commit refines the workaround to copy the file into the build
directory of the test task's project and reference it using a URL
that's relative to the task's working directory. This ensures that
the value of the system property doesn't change from build to build.

Closes gh-26252

buildSrc/src/main/java/org/springframework/boot/build/JavaConventions.java

@@ -17,6 +17,10 @@
 package org.springframework.boot.build;
 
 import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
@@ -28,8 +32,10 @@ import java.util.stream.Collectors;
 
 import io.spring.javaformat.gradle.FormatTask;
 import io.spring.javaformat.gradle.SpringJavaFormatPlugin;
+import org.gradle.api.Action;
 import org.gradle.api.JavaVersion;
 import org.gradle.api.Project;
+import org.gradle.api.Task;
 import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.artifacts.ConfigurationContainer;
 import org.gradle.api.artifacts.Dependency;
@@ -142,10 +148,14 @@ class JavaConventions {
 			withOptionalBuildJavaHome(project, (javaHome) -> test.setExecutable(javaHome + "/bin/java"));
 			test.useJUnitPlatform();
 			test.setMaxHeapSize("1024M");
+			CopyJdk8156584SecurityProperties copyJdk8156584SecurityProperties = new CopyJdk8156584SecurityProperties(
+					project);
 			if (buildingWithJava8(project)) {
 				test.systemProperty("java.security.properties",
-						getClass().getClassLoader().getResource("jdk-8156584-security.properties"));
+						"file:" + test.getWorkingDir().toPath().relativize(copyJdk8156584SecurityProperties.output));
+				test.setDebug(true);
 			}
+			test.doFirst(copyJdk8156584SecurityProperties);
 		});
 		project.getPlugins().withType(JavaPlugin.class, (javaPlugin) -> project.getDependencies()
 				.add(JavaPlugin.TEST_RUNTIME_ONLY_CONFIGURATION_NAME, "org.junit.platform:junit-platform-launcher"));
@@ -226,4 +236,27 @@ class JavaConventions {
 				.getByName(OptionalDependenciesPlugin.OPTIONAL_CONFIGURATION_NAME).extendsFrom(dependencyManagement));
 	}
 
+	private static final class CopyJdk8156584SecurityProperties implements Action<Task> {
+
+		private static final String SECURITY_PROPERTIES_FILE_NAME = "jdk-8156584-security.properties";
+
+		private final Path output;
+
+		private CopyJdk8156584SecurityProperties(Project project) {
+			this.output = new File(project.getBuildDir(), SECURITY_PROPERTIES_FILE_NAME).toPath();
+		}
+
+		@Override
+		public void execute(Task task) {
+			try (InputStream input = getClass().getClassLoader()
+					.getResourceAsStream(CopyJdk8156584SecurityProperties.SECURITY_PROPERTIES_FILE_NAME)) {
+				Files.copy(input, this.output);
+			}
+			catch (IOException ex) {
+				throw new RuntimeException(ex);
+			}
+		}
+
+	}
+
 }