Updated Shared symbol requests/subscriptions to allow multiple symbols in one call if supported

CryptoExchange.Net/SharedApis/Models/Options/Endpoints/EndpointOptions.cs

@@ -109,6 +109,15 @@ namespace CryptoExchange.Net.SharedApis
         /// </summary>
         public List<ParameterDescription> RequiredOptionalParameters { get; set; } = new List<ParameterDescription>();
 
+        /// <summary>
+        /// Whether this accepts multiple symbols (Only applicable to request requiring symbol parameters)
+        /// </summary>
+        public bool SupportsMultipleSymbols { get; set; } = false;
+        /// <summary>
+        /// The max number of symbols which can be passed in a call (Only applicable to request requiring symbol parameters)
+        /// </summary>
+        public int? MaxSymbolCount { get; set; }
+
         /// <summary>
         /// ctor
         /// </summary>
@@ -141,6 +150,19 @@ namespace CryptoExchange.Net.SharedApis
 
             }
 
+            if (request is SharedSymbolRequest symbolsRequest)
+            {
+                if (symbolsRequest.Symbols != null) 
+                {
+                    if (!SupportsMultipleSymbols)
+                        return new ArgumentError($"Only a single symbol parameter is allowed, multiple symbols are not supported");
+
+                    if (symbolsRequest.Symbols.Length > MaxSymbolCount)
+                        return new ArgumentError($"Max number of symbols is {MaxSymbolCount} but {symbolsRequest.Symbols.Length} were passed");
+                }
+
+            }
+
             return ValidateRequest(exchange, request.ExchangeParameters, tradingMode, supportedTradingModes);
         }