Allow empty credential values in requests

spring-credhub-core/src/main/java/org/springframework/credhub/support/CredentialRequest.java

@@ -18,6 +18,8 @@
 
 package org.springframework.credhub.support;
 
+import com.fasterxml.jackson.annotation.JsonInclude;
+
 /**
  * The details of a request to write a new or update an existing credential in CredHub.
  *
@@ -39,6 +41,7 @@ public class CredentialRequest<T> extends CredHubRequest<T> {
 	 *
 	 * @return the value of the credential
 	 */
+	@JsonInclude(JsonInclude.Include.NON_NULL)
 	public T getValue() {
 		return this.details;
 	}

spring-credhub-core/src/test/java/org/springframework/credhub/support/json/JsonCredentialRequestUnitTests.java

@@ -23,6 +23,9 @@ import org.junit.Test;
 import org.springframework.credhub.support.CredHubRequestUnitTestsBase;
 import org.springframework.credhub.support.SimpleCredentialName;
 import org.springframework.credhub.support.WriteMode;
+import org.springframework.credhub.support.json.JsonCredentialRequest.JsonCredentialRequestBuilder;
+
+import java.util.Collections;
 
 import static org.springframework.credhub.support.JsonPathAssert.assertThat;
 
@@ -32,17 +35,18 @@ public class JsonCredentialRequestUnitTests extends CredHubRequestUnitTestsBase
 	public void setUp() {
 		requestBuilder = JsonCredentialRequest.builder()
 				.name(new SimpleCredentialName("example", "credential"))
-				.value(new JsonCredential() {
-					{
-						put("data", "value");
-						put("test", true);
-					}
-				})
 				.mode(WriteMode.OVERWRITE);
 	}
 
 	@Test
 	public void serializeWithJsonValue() {
+		((JsonCredentialRequestBuilder) requestBuilder).value(new JsonCredential() {
+			{
+				put("data", "value");
+				put("test", true);
+			}
+		});
+
 		DocumentContext json = toJsonPath(requestBuilder);
 
 		assertCommonRequestFields(json, null, WriteMode.OVERWRITE, "/example/credential", "json");
@@ -51,4 +55,17 @@ public class JsonCredentialRequestUnitTests extends CredHubRequestUnitTestsBase
 
 		assertNoPermissions(json);
 	}
+
+	@Test
+	public void serializeWithEmptyValue() {
+		((JsonCredentialRequestBuilder) requestBuilder).value(new JsonCredential() {
+		});
+
+		DocumentContext json = toJsonPath(requestBuilder);
+
+		assertCommonRequestFields(json, null, WriteMode.OVERWRITE, "/example/credential", "json");
+		assertThat(json).hasPath("$.value").isEqualTo(Collections.EMPTY_MAP);
+
+		assertNoPermissions(json);
+	}
 }