Expose GetInteropDescriptor (#3545)

* Expose GetInteropDescriptor

* Update src/Neo/SmartContract/ApplicationEngine.cs

---------

Co-authored-by: Jimmy <jinghui@wayne.edu>
Co-authored-by: NGD Admin <154295625+NGDAdmin@users.noreply.github.com>

src/Neo/SmartContract/ApplicationEngine.cs

@@ -22,6 +22,7 @@
 using System.Linq;
 using System.Numerics;
 using System.Reflection;
+using System.Runtime.CompilerServices;
 using Array = System.Array;
 using VMArray = Neo.VM.Types.Array;
 
@@ -241,9 +242,7 @@ protected static void OnSysCall(ExecutionEngine engine, Instruction instruction)
         {
             if (engine is ApplicationEngine app)
             {
-                uint method = instruction.TokenU32;
-
-                app.OnSysCall(services[method]);
+                app.OnSysCall(GetInteropDescriptor(instruction.TokenU32));
             }
             else
             {
@@ -641,6 +640,17 @@ private static InteropDescriptor Register(string name, string handler, long fixe
             return descriptor;
         }
 
+        /// <summary>
+        /// Get Interop Descriptor
+        /// </summary>
+        /// <param name="methodHash">Method Hash</param>
+        /// <returns>InteropDescriptor</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static InteropDescriptor GetInteropDescriptor(uint methodHash)
+        {
+            return services[methodHash];
+        }
+
         /// <summary>
         /// Creates a new instance of the <see cref="ApplicationEngine"/> class, and use it to run the specified script.
         /// </summary>