all Process classes should also be static strings

Author: mr-c

CommandLineTool.yml

@@ -631,7 +631,11 @@ $graph:
       jsonldPredicate:
         "_id": "@type"
         "_type": "@vocab"
-      type: string
+      type:
+        type: enum
+        name: CommandLineTool_class
+        symbols:
+          - cwl:CommandLineTool
     - name: baseCommand
       doc: |
         Specifies the program to execute.  If an array, the first element of

Operation.yml

@@ -87,4 +87,8 @@ $graph:
       jsonldPredicate:
         "_id": "@type"
         "_type": "@vocab"
-      type: string
+      type:
+        type: enum
+        name: Operation_class
+        symbols:
+          - cwl:Operation

Workflow.yml

@@ -175,7 +175,11 @@ $graph:
       jsonldPredicate:
         "_id": "@type"
         "_type": "@vocab"
-      type: string
+      type:
+        type: enum
+        name: ExpressionTool_class
+        symbols:
+          - cwl:ExpressionTool
     - name: expression
       type: Expression
       doc: |
@@ -707,7 +711,11 @@ $graph:
       jsonldPredicate:
         "_id": "@type"
         "_type": "@vocab"
-      type: string
+      type:
+        type: enum
+        name: Workflow_class
+        symbols:
+          - cwl:Workflow
     - name: steps
       doc: |
         The individual steps that make up the workflow.  Each step is executed when all of its