Allow Gradle task property to be set with String or enum value

See gh-32769

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

@@ -68,6 +68,8 @@ public abstract class BootBuildImage extends DefaultTask {
 
 	private static final String BUILDPACK_JVM_VERSION_KEY = "BP_JVM_VERSION";
 
+	private final Property<PullPolicy> pullPolicy;
+
 	private final String projectName;
 
 	private final CacheSpec buildCache;
@@ -94,6 +96,7 @@ public abstract class BootBuildImage extends DefaultTask {
 		this.buildCache = getProject().getObjects().newInstance(CacheSpec.class);
 		this.launchCache = getProject().getObjects().newInstance(CacheSpec.class);
 		this.docker = getProject().getObjects().newInstance(DockerSpec.class);
+		this.pullPolicy = getProject().getObjects().property(PullPolicy.class);
 	}
 
 	/**
@@ -175,7 +178,17 @@ public abstract class BootBuildImage extends DefaultTask {
 	@Input
 	@Optional
 	@Option(option = "pullPolicy", description = "The image pull policy")
-	public abstract Property<String> getPullPolicy();
+	public Property<PullPolicy> getPullPolicy() {
+		return this.pullPolicy;
+	}
+
+	/**
+	 * Sets image pull policy that will be used when building the image.
+	 * @param pullPolicy the pull policy to use
+	 */
+	public void setPullPolicy(String pullPolicy) {
+		getPullPolicy().set(PullPolicy.valueOf(pullPolicy));
+	}
 
 	/**
 	 * Whether the built image should be pushed to a registry.
@@ -342,7 +355,7 @@ public abstract class BootBuildImage extends DefaultTask {
 	}
 
 	private BuildRequest customizePullPolicy(BuildRequest request) {
-		PullPolicy pullPolicy = getPullPolicy().map(PullPolicy::valueOf).getOrNull();
+		PullPolicy pullPolicy = getPullPolicy().getOrNull();
 		if (pullPolicy != null) {
 			request = request.withPullPolicy(pullPolicy);
 		}

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

@@ -216,7 +216,7 @@ class BootBuildImageTests {
 
 	@Test
 	void whenPullPolicyIsConfiguredThenRequestHasPullPolicy() {
-		this.buildImage.getPullPolicy().set(PullPolicy.NEVER.toString());
+		this.buildImage.getPullPolicy().set(PullPolicy.NEVER);
 		assertThat(this.buildImage.createRequest().getPullPolicy()).isEqualTo(PullPolicy.NEVER);
 	}
 

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/tasks/bundling/BootBuildImageIntegrationTests-buildsImageWithPullPolicy.gradle

@@ -1,3 +1,5 @@
+import org.springframework.boot.buildpack.platform.build.PullPolicy;
+
 plugins {
 	id 'java'
 	id 'org.springframework.boot' version '{version}'
@@ -12,4 +14,5 @@ targetCompatibility = '1.8'
 
 bootBuildImage {
 	builder = "projects.registry.vmware.com/springboot/spring-boot-cnb-builder:0.0.1"
+	pullPolicy = PullPolicy.ALWAYS
 }