More cleanup

Author: MaggieKimani1

src/Microsoft.OpenApi.Readers/OpenApiYamlDocumentReader.cs

@@ -193,7 +193,7 @@ public T ReadFragment<T>(YamlDocument input, OpenApiSpecVersion version, out Ope
             }
 
             // Validate the element
-            if (_settings.RuleSet != null && _settings.RuleSet.Rules.Count() > 0)
+            if (_settings.RuleSet != null && _settings.RuleSet.Rules.Any())
             {
                 var errors = element.Validate(_settings.RuleSet);
                 foreach (var item in errors)

src/Microsoft.OpenApi/Validations/ValidationRuleSet.cs

@@ -17,11 +17,11 @@ namespace Microsoft.OpenApi.Validations
     /// </summary>
     public sealed class ValidationRuleSet : IEnumerable<ValidationRule>
     {
-        private IDictionary<Type, IList<ValidationRule>> _rules = new Dictionary<Type, IList<ValidationRule>>();
+        private readonly IDictionary<Type, IList<ValidationRule>> _rules = new Dictionary<Type, IList<ValidationRule>>();
 
         private static ValidationRuleSet _defaultRuleSet;
 
-        private IList<ValidationRule> _emptyRules = new List<ValidationRule>();
+        private readonly IList<ValidationRule> _emptyRules = new List<ValidationRule>();
 
         /// <summary>
         /// Retrieve the rules that are related to a specific type