Remove thinTaskExecutionList from TaskTemplate (spring-attic#5842)

ThinTaskExecutions are not a part of SCDF-3.0.x.
During the migration some of the ThinTaskExecution URL calls were left in the rest client and this caused some test failures in IT.
This PR removes the API access from the client for ThinTaskExecutions.

Author: cppwfs

spring-cloud-dataflow-rest-client/src/main/java/org/springframework/cloud/dataflow/rest/client/TaskOperations.java

@@ -108,11 +108,6 @@ public interface TaskOperations {
 	 */
 	PagedModel<TaskExecutionResource> executionList();
 
-	/**
-	 * @return the list of thin task executions known to the system.
-	 */
-	PagedModel<TaskExecutionThinResource> thinExecutionList();
-
 	/**
 	 * List task executions known to the system filtered by task name.
 	 *

spring-cloud-dataflow-rest-client/src/main/java/org/springframework/cloud/dataflow/rest/client/TaskTemplate.java

@@ -69,8 +69,6 @@ public class TaskTemplate implements TaskOperations {
 	private static final String VALIDATION_THIN_TASK_VERSION = "2.11.3";
 	private static final String EXECUTIONS_RELATION = "tasks/executions";
 
-	private static final String THIN_EXECUTIONS_RELATION = "tasks/thinexecutions";
-
 	private static final String EXECUTIONS_CURRENT_RELATION = "tasks/executions/current";
 
 	private static final String EXECUTION_RELATION = "tasks/executions/execution";
@@ -95,8 +93,6 @@ public class TaskTemplate implements TaskOperations {
 
 	private final Link executionsLink;
 
-	private final Link thinExecutionsLink;
-
 	private final Link executionLink;
 
 	private final Link executionLaunchLink;
@@ -131,8 +127,7 @@ public class TaskTemplate implements TaskOperations {
 			EXECUTIONS_INFO_RELATION,
 			PLATFORM_LIST_RELATION,
 			RETRIEVE_LOG,
-			VALIDATION_REL,
-			THIN_EXECUTIONS_RELATION
+			VALIDATION_REL
 		).forEach(relation -> {
 			Assert.isTrue(resources.getLink(relation).isPresent(), () -> relation + " relation is required");
 		});
@@ -147,12 +142,7 @@ public class TaskTemplate implements TaskOperations {
 		} else {
 			this.executionsCurrentLink = null;
 		}
-		if(VersionUtils.isDataFlowServerVersionGreaterThanOrEqualToRequiredVersion(version, VALIDATION_THIN_TASK_VERSION)) {
-			Assert.isTrue(resources.getLink(THIN_EXECUTIONS_RELATION).isPresent(), () -> THIN_EXECUTIONS_RELATION + " relation is required");
-			this.thinExecutionsLink = resources.getLink(THIN_EXECUTIONS_RELATION).get();
-		} else {
-			this.thinExecutionsLink = null;
-		}
+
 		this.restTemplate = restTemplate;
 		this.aboutLink = resources.getLink("about").get();
 		this.definitionsLink = resources.getLink(DEFINITIONS_RELATION).get();
@@ -265,11 +255,6 @@ public TaskExecutionResource.Page executionList() {
 		return restTemplate.getForObject(executionsLink.getHref(), TaskExecutionResource.Page.class);
 	}
 
-	@Override
-	public PagedModel<TaskExecutionThinResource> thinExecutionList() {
-		return restTemplate.getForObject(thinExecutionsLink.getHref(), TaskExecutionThinResource.Page.class);
-	}
-
 	@Override
 	public TaskExecutionResource.Page executionListByTaskName(String taskName) {
 		return restTemplate.getForObject(executionByNameLink.expand(taskName).getHref(),