Add support for load_var step

See: #633

headless-services/concourse-language-server/src/main/java/org/springframework/ide/vscode/concourse/PipelineYmlSchema.java

@@ -367,10 +367,16 @@ public PipelineYmlSchema(ConcourseModel models, GithubInfoProvider github) {
 
 		YBeanType setPipelineStep = f.ybean("SetPipelineStep");
 		addProp(setPipelineStep, "set_pipeline", t_ne_string);
-		addProp(setPipelineStep, "file", t_string).isRequired(true);
+		addProp(setPipelineStep, "file", t_ne_string).isRequired(true);
 		addProp(setPipelineStep, "vars", t_params);
 		addProp(setPipelineStep, "var_files", t_strings);
 
+		YBeanType loadVarStep = f.ybean("LoadVarStep");
+		addProp(loadVarStep, "load_var", t_ne_string); //TODO: t_identifier: see https://concourse-ci.org/config-basics.html#schema.identifier
+		addProp(loadVarStep, "file", t_ne_string).isRequired(true);
+		addProp(loadVarStep, "format", f.yenum("LoadVarFormat", "json", "yaml", "yml", "trim", "raw"));
+		addProp(loadVarStep, "reveal", t_boolean);
+
 		YBeanType aggregateStep = f.ybean("AggregateStep");
 		YBeanType doStep = f.ybean("DoStep");
 		YBeanType tryStep = f.ybean("TryStep");
@@ -381,12 +387,14 @@ public PipelineYmlSchema(ConcourseModel models, GithubInfoProvider github) {
 				putStep,
 				taskStep,
 				setPipelineStep,
+				loadVarStep,
 				aggregateStep,
 				inParallelStep,
 				doStep,
 				tryStep
 		};
 
+
 
 		YBeanUnionType step = f.yBeanUnion("Step", stepTypes);
 		addProp(aggregateStep, "aggregate", f.yseq(step)).isDeprecated("Deprecated in favor of `in_parallel`");

headless-services/concourse-language-server/src/main/resources/desc/LoadVarStep/file.md

@@ -0,0 +1 @@
+*Required*. The path to a file whose content shall be read and used as the var's value.

headless-services/concourse-language-server/src/main/resources/desc/LoadVarStep/format.md

@@ -0,0 +1,35 @@
+*Optional*. The format of the file's content.
+
+If unset, Concourse will try to detect the format from the file extension. If the file format cannot be determined, Concourse will fallback to `trim`.
+
+If set to `json`, `yaml`, or `yml`, the file content will be parsed accordingly and the resulting structure will be the value of the var.
+
+If set to `trim`, the var will be set to the content of the file with any trailing and leading whitespace removed.
+
+If set to `raw`, the var will be set to the content of the file without modification (i.e. with any existing whitespace).
+
+**Example**: Loading a var with multiple fields.
+
+Let's say we have a task, `generate-creds`, which produces a `generated-user` output containing a `user.json` file like so:
+
+```
+{
+  "username": "some-user",
+  "password": "some-password"
+}
+```
+
+We could pass these credentials to subsequent steps by loading it into a var with `load_var`, which will detect that it is in JSON format based on the file extension:
+
+```
+plan:
+- task: generate-creds
+- load_var: user
+  file: generated-user/user.json
+- task: use-creds
+  params:
+    USERNAME: ((.:user.username))
+    PASSWORD: ((.:user.password))
+```
+
+If the `use-creds` task were to print these values, they would be automatically redacted unless `reveal: true` is set.

headless-services/concourse-language-server/src/main/resources/desc/LoadVarStep/load_var.md

@@ -0,0 +1,14 @@
+Note: The `load_var` step was introduced in Concourse v6.0.0. It is considered an experimental feature until its associated [RFC](https://github.com/concourse/rfcs/pull/27) is resolved.
+
+*Required* Load the value for a var at runtime, making it available to subsequent steps as a build-local var named after the given identifier.
+
+The following build plan uses a version produced by the semver resource as a tag:
+
+```
+plan:
+- get: version
+- load_var: version-tag
+  file: version/version
+- put: image
+  params: {tag: ((.:version-tag))}
+```

headless-services/concourse-language-server/src/main/resources/desc/LoadVarStep/reveal.md

@@ -0,0 +1 @@
+*Optional*. *Default: false*. If set to `true`, allow the var's content to be printed in the build output even with secret redaction enabled.

headless-services/concourse-language-server/src/test/java/org/springframework/ide/vscode/concourse/ConcourseEditorTest.java

@@ -371,6 +371,8 @@ public void primaryStepCompletions() throws Exception {
 				"in_parallel:\n" +
 				"      <*>"
 				, // ==============
+				"load_var: <*>"
+				, // ==============
 				"put: <*>"
 				, // ==============
 				"set_pipeline: <*>"
@@ -400,7 +402,7 @@ public void PT_136196057_do_step_completion_indentation() throws Exception {
 				"    - <*>"
 		);
 	}
-
+	
 	@Test
 	public void primaryStepHovers() throws Exception {
 		Editor editor = harness.newEditor(
@@ -417,7 +419,9 @@ public void primaryStepHovers() throws Exception {
 				"  - try:\n" +
 				"      put: test-logs\n" +
 				"  - set_pipeline: configure-the-pipeline\n" +
-				"    file: my-repo/ci/pipeline.yml\n"
+				"    file: my-repo/ci/pipeline.yml\n" +
+				"  - load_var: some-var\n" +
+				"    file: /path/to/var-file\n"
 		);
 
 		editor.assertHoverContains("get", "Fetches a resource");
@@ -470,6 +474,50 @@ public void setPipelineStepHovers() throws Exception {
 		editor.assertHoverContains("var_files", "files that will be passed to the pipeline config in the same manner as the --load-vars-from flag");
 		editor.assertHoverContains("vars", "A map of template variables to pass to the pipeline config.");
 	}
+
+	@Test
+	public void loadVarStepHovers() throws Exception {
+		Editor editor = harness.newEditor(
+			"jobs:\n" +
+			"- name: some-job\n" +
+			"  plan:\n" +
+			"  - get: my-repo\n" +
+			"  - load_var: some-var\n" +
+			"    file: path/to/varfile.json\n" +
+			"    format: json\n" +
+			"    reveal: true\n"
+		);
+
+		editor.assertHoverContains("load_var", "Load the value for a var at runtime");
+		editor.assertHoverContains("file", "file whose content shall be read");
+		editor.assertHoverContains("format", "The format of the file's content");
+		editor.assertHoverContains("reveal", "allow the var's content to be printed");			
+	}
+
+	@Test
+	public void loadVarStepReconcile() throws Exception {
+		Editor editor = harness.newEditor(
+			"jobs:\n" +
+			"- name: some-job\n" +
+			"  plan:\n" +
+			"  - load_var: some-var\n"
+		);
+		editor.assertProblems("-^ load_var|'file' is required");
+
+		editor = harness.newEditor(
+			"jobs:\n" +
+			"- name: some-job\n" +
+			"  plan:\n" +
+			"  - load_var: some-var\n" +
+			"    file: path/to/varfile.json\n" +
+			"    format: a-format\n" +
+			"    reveal: show-it\n"
+		);
+		editor.assertProblems(
+				"a-format|Valid values are: [json, raw, trim, yaml, yml]",
+				"show-it|boolean"
+		);
+	}
 
 	@Test
 	public void getStepHovers() throws Exception {
@@ -4283,6 +4331,7 @@ public void taskWithYamlParams() throws Exception {
 				"- do",
 				"- get",
 				"- in_parallel",
+				"- load_var\n" + 
 				"- put",
 				"- set_pipeline",
 				"- task",