Use only MapProperty, delete setters and let gradle do the magic

jib-gradle-plugin/src/main/java/com/google/cloud/tools/jib/gradle/ContainerParameters.java

@@ -27,7 +27,6 @@
 import javax.inject.Inject;
 import org.gradle.api.model.ObjectFactory;
 import org.gradle.api.provider.MapProperty;
-import org.gradle.api.provider.Provider;
 import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.Optional;
 
@@ -204,20 +203,14 @@ public void setVolumes(List<String> volumes) {
 
   @Input
   @Optional
-  public Map<String, String> getLabels() {
-    if (System.getProperty(PropertyNames.CONTAINER_LABELS) != null) {
-      return ConfigurationPropertyValidator.parseMapProperty(
-          System.getProperty(PropertyNames.CONTAINER_LABELS));
+  public MapProperty<String, String> getLabels() {
+    String labelsProperty = System.getProperty(PropertyNames.CONTAINER_LABELS);
+    if (labelsProperty != null) {
+      Map<String, String> parsedLabels =
+          ConfigurationPropertyValidator.parseMapProperty(labelsProperty);
+      labels.set(parsedLabels);
     }
-    return labels.get();
-  }
-
-  public void setLabels(Map<String, String> labels) {
-    this.labels.set(labels);
-  }
-
-  public void setLabels(Provider<Map<String, String>> labels) {
-    this.labels.set(labels);
+    return labels;
   }
 
   @Input

jib-gradle-plugin/src/main/java/com/google/cloud/tools/jib/gradle/GradleRawConfiguration.java

@@ -113,7 +113,7 @@ public Map<String, String> getEnvironment() {
 
   @Override
   public Map<String, String> getLabels() {
-    return jibExtension.getContainer().getLabels();
+    return jibExtension.getContainer().getLabels().get();
   }
 
   @Override

jib-gradle-plugin/src/test/java/com/google/cloud/tools/jib/gradle/GradleRawConfigurationTest.java

@@ -23,6 +23,7 @@
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.HashSet;
+import org.gradle.api.internal.provider.DefaultMapProperty;
 import org.junit.Assert;
 import org.junit.Test;
 import org.mockito.Mockito;
@@ -67,8 +68,10 @@ public void testGetters() {
     Mockito.when(containerParameters.getEnvironment())
         .thenReturn(new HashMap<>(ImmutableMap.of("currency", "dollar")));
     Mockito.when(containerParameters.getJvmFlags()).thenReturn(Arrays.asList("-cp", "."));
-    Mockito.when(containerParameters.getLabels())
-        .thenReturn(new HashMap<>(ImmutableMap.of("unit", "cm")));
+    DefaultMapProperty<String, String> labelProperties =
+        new DefaultMapProperty<>(String.class, String.class);
+    labelProperties.set(new HashMap<>(ImmutableMap.of("unit", "cm")));
+    Mockito.when(containerParameters.getLabels()).thenReturn(labelProperties);
     Mockito.when(containerParameters.getMainClass()).thenReturn("com.example.Main");
     Mockito.when(containerParameters.getPorts()).thenReturn(Arrays.asList("80/tcp", "0"));
     Mockito.when(containerParameters.getUser()).thenReturn("admin:wheel");

jib-gradle-plugin/src/test/java/com/google/cloud/tools/jib/gradle/JibExtensionTest.java

@@ -140,7 +140,6 @@ public void testContainer() {
     assertThat(testJibExtension.getContainer().getArgs()).isNull();
     assertThat(testJibExtension.getContainer().getFormat()).isSameInstanceAs(ImageFormat.Docker);
     assertThat(testJibExtension.getContainer().getPorts()).isEmpty();
-    assertThat(testJibExtension.getContainer().getLabels()).isEmpty();
     assertThat(testJibExtension.getContainer().getAppRoot()).isEmpty();
     assertThat(testJibExtension.getContainer().getFilesModificationTime())
         .isEqualTo("EPOCH_PLUS_SECOND");
@@ -156,7 +155,6 @@ public void testContainer() {
           container.setMainClass("mainClass");
           container.setArgs(Arrays.asList("arg1", "arg2", "arg3"));
           container.setPorts(Arrays.asList("1000", "2000-2010", "3000"));
-          container.setLabels(ImmutableMap.of("label1", "value1", "label2", "value2"));
           container.setFormat(ImageFormat.OCI);
           container.setAppRoot("some invalid appRoot value");
           container.setFilesModificationTime("some invalid time value");
@@ -172,9 +170,6 @@ public void testContainer() {
     assertThat(testJibExtension.getContainer().getMainClass()).isEqualTo("mainClass");
     assertThat(container.getArgs()).containsExactly("arg1", "arg2", "arg3").inOrder();
     assertThat(container.getPorts()).containsExactly("1000", "2000-2010", "3000").inOrder();
-    assertThat(container.getLabels())
-        .containsExactly("label1", "value1", "label2", "value2")
-        .inOrder();
     assertThat(container.getFormat()).isSameInstanceAs(ImageFormat.OCI);
     assertThat(container.getAppRoot()).isEqualTo("some invalid appRoot value");
     assertThat(container.getFilesModificationTime()).isEqualTo("some invalid time value");
@@ -379,7 +374,11 @@ public void testProperties() {
         .containsExactly("flag1", "flag2", "flag3")
         .inOrder();
     System.setProperty("jib.container.labels", "label1=val1,label2=val2");
-    assertThat(testJibExtension.getContainer().getLabels())
+    assertThat(testJibExtension.getContainer().getLabels().get())
+        .containsExactly("label1", "val1", "label2", "val2")
+        .inOrder();
+    System.clearProperty("jib.container.labels");
+    assertThat(testJibExtension.getContainer().getLabels().get())
         .containsExactly("label1", "val1", "label2", "val2")
         .inOrder();
     System.setProperty("jib.container.mainClass", "main");

jib-gradle-plugin/src/test/resources/gradle/projects/lazy-evaluation/build.gradle

@@ -36,6 +36,6 @@ jib {
 }
 
 tasks.register('showlabels') {
-    Map<String, String> prop = project.extensions.getByName("jib")["container"]["labels"]
+    Map<String, String> prop = project.extensions.getByName("jib")["container"]["labels"].get()
     println("labels contain values " + prop)
 }