[TA] Implement docstring for healthcare assertion (Azure#21442)

Author: maririos

sdk/textanalytics/Azure.AI.TextAnalytics/api/Azure.AI.TextAnalytics.netstandard2.0.cs

@@ -267,6 +267,7 @@ internal HealthcareEntityAssertion() { }
         public Azure.AI.TextAnalytics.EntityAssociation? Association { get { throw null; } }
         public Azure.AI.TextAnalytics.EntityCertainty? Certainty { get { throw null; } }
         public Azure.AI.TextAnalytics.EntityConditionality? Conditionality { get { throw null; } }
+        public override string ToString() { throw null; }
     }
     public partial class HealthcareEntityRelation
     {

sdk/textanalytics/Azure.AI.TextAnalytics/src/HealthcareEntityAssertion.cs

@@ -1,7 +1,6 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
-using System.Collections.Generic;
 using Azure.Core;
 
 namespace Azure.AI.TextAnalytics
@@ -11,5 +10,15 @@ namespace Azure.AI.TextAnalytics
     /// Exposes <see cref="EntityConditionality"/>, <see cref="EntityAssociation"/> and <see cref="EntityCertainty"/>.
     /// </summary>
     [CodeGenModel("HealthcareAssertion")]
-    public partial class HealthcareEntityAssertion { }
+    public partial class HealthcareEntityAssertion
+    {
+        /// <summary>
+        /// Returns a string that contains the values for the
+        /// <see cref="HealthcareEntityAssertion"/> object.
+        /// </summary>
+        public override string ToString()
+        {
+            return $"{nameof(Association)}:'{Association}', {nameof(Certainty)}:'{Certainty}', {nameof(Conditionality)}:'{Conditionality}'";
+        }
+    }
 }