change apiId to required parameter

Author: solankisamir

src/ApiManagement/ApiManagement.ServiceManagement/Commands/GetAzureApiManagementProduct.cs

@@ -53,7 +53,7 @@ public class GetAzureApiManagementProduct : AzureApiManagementCmdletBase
         [Parameter(
             ParameterSetName = GetByApiId,
             ValueFromPipelineByPropertyName = true,
-            Mandatory = false,
+            Mandatory = true,
             HelpMessage = "ApiId of the Api to find the correlated products. This parameter is optional.")]
         public String ApiId { get; set; }
 

src/ApiManagement/ApiManagement/help/Get-AzApiManagementProduct.md

@@ -33,7 +33,7 @@ Get-AzApiManagementProduct -Context <PsApiManagementContext> [-Title <String>]
 
 ### GetByApiId
 ```
-Get-AzApiManagementProduct -Context <PsApiManagementContext> [-ApiId <String>]
+Get-AzApiManagementProduct -Context <PsApiManagementContext> -ApiId <String>
  [-DefaultProfile <IAzureContextContainer>] [<CommonParameters>]
 ```
 
@@ -68,7 +68,7 @@ Type: System.String
 Parameter Sets: GetByApiId
 Aliases:
 
-Required: False
+Required: True
 Position: Named
 Default value: None
 Accept pipeline input: True (ByPropertyName)