"id" is a required field in for Parameters and WorkflowSteps (#300)

Author: mr-c

Process.yml

@@ -71,6 +71,17 @@ $graph:
       doc: "The unique identifier for this object."
 
 
+- name: IdentifierRequired
+  type: record
+  extends: [Identified]
+  abstract: true
+  fields:
+    - name: id
+      type: string
+      jsonldPredicate: "@id"
+      doc: "The unique identifier for this object."
+
+
 - name: LoadListingEnum
   type: enum
   symbols: [no_listing, shallow_listing, deep_listing]
@@ -232,10 +243,15 @@ $graph:
 
 - name: Parameter
   type: record
-  extends: [FieldBase, sld:Documented, Identified]
+  extends: [FieldBase, sld:Documented, IdentifierRequired]
   abstract: true
   doc: |
     Define an input or output parameter to a process.
+  fields:
+    - name: id
+      type: string
+      jsonldPredicate: "@id"
+      doc: "The unique identifier for this Parameter."
 
 
 - type: enum

Workflow.yml

@@ -471,7 +471,7 @@ $graph:
 
 - type: record
   name: WorkflowStepInput
-  extends: [Identified, Sink, LoadContents, Labeled]
+  extends: [IdentifierRequired, Sink, LoadContents, Labeled]
   docParent: "#WorkflowStep"
   doc: |
     The input of a workflow step connects an upstream parameter (from the
@@ -584,6 +584,10 @@ $graph:
        should be filtered out.
 
   fields:
+    - name: id
+      type: string
+      jsonldPredicate: "@id"
+      doc: "The unique identifier of the source input field name."
     - name: default
       type: CWLObjectType?
       doc: |
@@ -628,7 +632,7 @@ $graph:
 - type: record
   name: WorkflowStepOutput
   docParent: "#WorkflowStep"
-  extends: Identified
+  extends: IdentifierRequired
   doc: |
     Associate an output parameter of the underlying process with a workflow
     parameter.  The workflow parameter (given in the `id` field) be may be used
@@ -638,6 +642,11 @@ $graph:
     A unique identifier for this workflow output parameter.  This is
     the identifier to use in the `source` field of `WorkflowStepInput`
     to connect the output value to downstream parameters.
+  fields:
+    - name: id
+      type: string
+      jsonldPredicate: "@id"
+      doc: "The unique identifier of the workflow parameter to export."
 
 
 - name: ScatterMethod
@@ -652,7 +661,7 @@ $graph:
 
 - name: WorkflowStep
   type: record
-  extends: [Identified, Labeled, sld:Documented]
+  extends: [IdentifierRequired, Labeled, sld:Documented]
   docParent: "#Workflow"
   doc: |
     A workflow step is an executable element of a workflow.  It specifies the
@@ -736,6 +745,10 @@ $graph:
     a subworkflow (recursive workflows are not allowed).
 
   fields:
+    - name: id
+      type: string
+      jsonldPredicate: "@id"
+      doc: "The unique identifier for this WorkflowStep."
     - name: in
       type: WorkflowStepInput[]
       jsonldPredicate: