Adds support for optional parameters for operations (#195)

* Add Odata.Core.V1.OptionalParameter

* Optional parameters could be optional and marked in: query

* Add test to validate optional parameters

* Remove unnecessary code

* PR review suggestion

Author: irvinesunday

src/Microsoft.OpenApi.OData.Reader/Generator/OpenApiParameterGenerator.cs

@@ -11,7 +11,6 @@
 using Microsoft.OpenApi.OData.Common;
 using Microsoft.OData.Edm.Vocabularies;
 using Microsoft.OpenApi.OData.Edm;
-using Microsoft.OpenApi.OData.Vocabulary;
 using Microsoft.OpenApi.OData.Vocabulary.Capabilities;
 
 namespace Microsoft.OpenApi.OData.Generator
@@ -70,7 +69,7 @@ public static IList<OpenApiParameter> CreateParameters(this ODataContext context
             Utils.CheckArgumentNull(context, nameof(context));
             Utils.CheckArgumentNull(function, nameof(function));
 
-            IList<OpenApiParameter> parameters = new List<OpenApiParameter>();
+            IList<OpenApiParameter> parameters = new List<OpenApiParameter>();            
             int skip = function.IsBound ? 1 : 0;
             foreach (IEdmOperationParameter edmParameter in function.Parameters.Skip(skip))
             {
@@ -80,7 +79,7 @@ public static IList<OpenApiParameter> CreateParameters(this ODataContext context
                     {
                         continue;
                     }
-                }
+                }                
 
                 OpenApiParameter parameter;
                 // Structured or collection-valued parameters are represented as a parameter alias
@@ -125,11 +124,12 @@ public static IList<OpenApiParameter> CreateParameters(this ODataContext context
                 else
                 {
                     // Primitive parameters use the same type mapping as described for primitive properties.
+                    bool isOptionalParameter = edmParameter is IEdmOptionalParameter;
                     parameter = new OpenApiParameter
                     {
                         Name = parameterNameMapping == null ? edmParameter.Name : parameterNameMapping[edmParameter.Name],
-                        In = ParameterLocation.Path,
-                        Required = true,
+                        In = isOptionalParameter ? ParameterLocation.Query : ParameterLocation.Path,
+                        Required = !isOptionalParameter,
                         Schema = context.CreateEdmTypeSchema(edmParameter.Type)
                     };
                 }

test/Microsoft.OpenAPI.OData.Reader.Tests/Generator/OpenApiParameterGeneratorTests.cs

@@ -375,7 +375,7 @@ public void CreateParametersWorks()
         {
             // Arrange
             IEdmModel model = EdmModelHelper.GraphBetaModel;
-            ODataContext context = new ODataContext(model);
+            ODataContext context = new(model);
             IEdmSingleton deviceMgmt = model.EntityContainer.FindSingleton("deviceManagement");
             Assert.NotNull(deviceMgmt);
 
@@ -385,9 +385,13 @@ public void CreateParametersWorks()
             IEdmFunction function2 = model.SchemaElements.OfType<IEdmFunction>().First(f => f.Name == "getRoleScopeTagsByResource");
             Assert.NotNull(function2);
 
+            IEdmFunction function3 = model.SchemaElements.OfType<IEdmFunction>().First(f => f.Name == "roleScheduleInstances");
+            Assert.NotNull(function3);
+
             // Act
             IList<OpenApiParameter> parameters1 = context.CreateParameters(function1);
             IList<OpenApiParameter> parameters2 = context.CreateParameters(function2);
+            IList<OpenApiParameter> parameters3 = context.CreateParameters(function3);
 
             // Assert
             Assert.NotNull(parameters1);
@@ -396,6 +400,10 @@ public void CreateParametersWorks()
             Assert.NotNull(parameters2);
             OpenApiParameter parameter2 = Assert.Single(parameters2);
 
+            Assert.NotNull(parameters3);
+            Assert.Equal(4, parameters3.Count);
+            OpenApiParameter parameter3 = parameters3.First();
+
             string json1 = parameter1.SerializeAsJson(OpenApiSpecVersion.OpenApi3_0);
             string expectedPayload1 = $@"{{
   ""name"": ""ids"",
@@ -425,8 +433,19 @@ public void CreateParametersWorks()
   }}
 }}";
 
+            string json3 = parameter3.SerializeAsJson(OpenApiSpecVersion.OpenApi3_0);
+            string expectedPayload3 = $@"{{
+  ""name"": ""directoryScopeId"",
+  ""in"": ""query"",
+  ""schema"": {{
+    ""type"": ""string"",
+    ""nullable"": true
+  }}
+}}";
+
             Assert.Equal(expectedPayload1.ChangeLineBreaks(), json1);
             Assert.Equal(expectedPayload2.ChangeLineBreaks(), json2);
+            Assert.Equal(expectedPayload3.ChangeLineBreaks(), json3);
         }
 
         public static IEdmModel GetEdmModel()