fix fabric8io#4136: updates based upon the review

kubernetes-client-api/src/main/java/io/fabric8/kubernetes/client/dsl/FieldValidateable.java

@@ -18,14 +18,14 @@
 public interface FieldValidateable<T> {
 
   public enum Validation {
-    WARN,
-    IGNORE,
-    STRICT;
+    WARN("Warn"),
+    IGNORE("Ignore"),
+    STRICT("Strict");
 
     String parameterValue;
 
-    private Validation() {
-      this.parameterValue = this.name().charAt(0) + this.name().toLowerCase().substring(1);
+    private Validation(String parameterValue) {
+      this.parameterValue = parameterValue;
     }
 
     public String parameterValue() {

kubernetes-itests/src/test/java/io/fabric8/kubernetes/FieldValidationIT.java

@@ -0,0 +1,50 @@
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.fabric8.kubernetes;
+
+import io.fabric8.junit.jupiter.api.RequireK8sVersionAtLeast;
+import io.fabric8.kubernetes.api.model.ConfigMap;
+import io.fabric8.kubernetes.api.model.ConfigMapBuilder;
+import io.fabric8.kubernetes.client.KubernetesClient;
+import io.fabric8.kubernetes.client.KubernetesClientException;
+import io.fabric8.kubernetes.client.dsl.FieldValidateable.Validation;
+import io.fabric8.kubernetes.client.dsl.NonDeletingOperation;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+@RequireK8sVersionAtLeast(majorVersion = 1, minorVersion = 25)
+class FieldValidationIT {
+
+  KubernetesClient client;
+
+  @Test
+  void create() {
+    // Given
+    ConfigMap configMap = new ConfigMapBuilder()
+        .withNewMetadata().withName("invalid").endMetadata().addToData("key", "value").build();
+    // add an unknown field
+    configMap.setAdditionalProperty("unknown", "field");
+
+    // When
+    NonDeletingOperation<ConfigMap> fieldValidation = client.configMaps().resource(configMap)
+        .fieldValidation(Validation.STRICT);
+
+    // Then
+    assertThrows(KubernetesClientException.class, () -> fieldValidation.create());
+  }
+
+}