updated schema and ComponentValidationTest files.

config/schema/experience_builder.schema.yml

@@ -404,10 +404,12 @@ experience_builder.generated_field_explicit_input_ux:
           # The default value must be retrievable
           expression:
             type: string
-            label: ''
-            constraints: { }
-            # @todo Add `StructuredDataPropExpression` validation constraint that fails if StructuredDataPropExpression::fromString() fails
-            # StructuredDataPropExpression: [field_type]
+            label: 'The expression'
+            constraints: 
+              ValidStructuredDataPropExpression:
+              - FieldTypePropExpression
+              - FieldTypeObjectPropsExpression
+              - ReferenceFieldTypePropExpression
 
 experience_builder.component_source_settings.js:
   constraints: