Change the property getter to only get the default style value if missing from a file but doesn't set it

Author: MaggieKimani1

src/Microsoft.OpenApi/Models/OpenApiParameter.cs

@@ -16,7 +16,7 @@ namespace Microsoft.OpenApi.Models
     public class OpenApiParameter : IOpenApiSerializable, IOpenApiReferenceable, IEffective<OpenApiParameter>, IOpenApiExtensible
     {
         private bool? _explode;
-        public ParameterStyle? _style;
+        private ParameterStyle? _style;
 
         /// <summary>
         /// Indicates if object is populated with data or is just a reference to the data
@@ -75,8 +75,8 @@ public class OpenApiParameter : IOpenApiSerializable, IOpenApiReferenceable, IEf
         /// for cookie - form.
         /// </summary>
         public ParameterStyle? Style
-        { 
-            get => _style ?? SetDefaultStyleValue();
+        {
+            get => _style ?? GetDefaultStyleValue();
             set => _style = value;
         }
 
@@ -401,7 +401,7 @@ public void SerializeAsV2WithoutReference(IOpenApiWriter writer)
             writer.WriteEndObject();
         }
 
-        private ParameterStyle? SetDefaultStyleValue()
+        private ParameterStyle? GetDefaultStyleValue()
         {
             Style = In switch
             {
@@ -411,7 +411,7 @@ public void SerializeAsV2WithoutReference(IOpenApiWriter writer)
                 ParameterLocation.Cookie => (ParameterStyle?)ParameterStyle.Form,
                 _ => (ParameterStyle?)ParameterStyle.Simple,
             };
-
+            
             return Style;
         }