Allow modeled types to be used for Union inputs.

gems/aws-sdk-core/CHANGELOG.md

@@ -1,6 +1,7 @@
 Unreleased Changes
 ------------------
 
+* Issue - Allow modeled types to be used for Union inputs.
 * Issue - Ensure that nested sensitive members and sensitive members of lists and maps are filtered.
 
 3.201.1 (2024-07-05)

gems/aws-sdk-core/lib/aws-sdk-core/param_validator.rb

@@ -71,7 +71,7 @@ def structure(ref, values, errors, context)
         end
 
         if @validate_required && shape.union
-          set_values = @input ? values.length : values.to_h.length
+          set_values = values.to_h.length
           if set_values > 1
             errors << "multiple values provided to union at #{context} - must contain exactly one of the supported types: #{shape.member_names.join(', ')}"
           elsif set_values == 0

gems/aws-sdk-core/spec/aws/param_validator_spec.rb

@@ -8,7 +8,11 @@ class TestClass; end
   describe ParamValidator do
     let(:shapes) { ApiHelper.sample_shapes }
 
-    let(:api) { ApiHelper.sample_api(shapes: shapes) }
+    let(:service) { ApiHelper.sample_service(shapes: shapes) }
+
+    let(:api) { service.const_get(:ClientApi).const_get(:API) }
+
+    let(:types) { service.const_get(:Types) }
 
     def validate(params, expected_errors = [])
       rules = api.operation(:example_operation).input
@@ -98,10 +102,16 @@ def match_errors(error, expected_errors)
         validate({ string: 's', boolean: true }, 'multiple values provided to union')
       end
 
-      it 'access a struct with exactly one value set' do
+      it 'accepts a struct with exactly one value set' do
         shapes['StructureShape']['union'] = true
         validate({ string: 's' })
       end
+
+      it 'accepts a modeled type' do
+        shapes['StructureShape']['union'] = true
+        input = types.const_get('StructureShape').new(string: 's')
+        validate(input)
+      end
     end
 
     describe 'lists' do