add Watermark support

CloudConvert.API/Models/TaskOperations/WatermarkCreateRequest.cs

@@ -0,0 +1,54 @@
+using Newtonsoft.Json;
+using Newtonsoft.Json.Converters;
+using System.Collections.Generic;
+using CloudConvert.API.Models.Enums;
+
+namespace CloudConvert.API.Models.TaskOperations
+{
+  public class WatermarkCreateRequest
+  {
+    [JsonProperty("operation")]
+    public static string Operation = "watermark";
+
+    /// <summary>
+    /// The input task name(s) for this task.
+    /// input: string | string[];
+    /// </summary>
+    [JsonProperty("input")]
+    public dynamic Input { get; set; }
+
+    /// <summary>
+    /// If not set, the extension of the input file is used as input format
+    /// </summary>
+    [JsonProperty("input_format", NullValueHandling = NullValueHandling.Ignore)]
+    public string Input_Format { get; set; }
+
+
+    [JsonProperty("engine", NullValueHandling = NullValueHandling.Ignore)]
+    public string Engine { get; set; }
+
+    [JsonProperty("engine_version", NullValueHandling = NullValueHandling.Ignore)]
+    public string Engine_Version { get; set; }
+
+    /// <summary>
+    /// Choose a filename (including extension) for the output file.
+    /// </summary>
+    [JsonProperty("filename", NullValueHandling = NullValueHandling.Ignore)]
+    public string Filename { get; set; }
+
+    /// <summary>
+    /// Timeout in seconds after the task will be cancelled.
+    /// </summary>
+    [JsonProperty("timeout", NullValueHandling = NullValueHandling.Ignore)]
+    public int? Timeout { get; set; }
+
+    /// <summary>
+    /// Conversion and engine specific options. Depends on input_format and output_format.
+    /// Select input and output format above to show additional conversion options.
+    /// </summary>
+    [JsonExtensionData]
+    [JsonProperty("options", NullValueHandling = NullValueHandling.Ignore)]
+    public Dictionary<string, object> Options { get; set; }
+
+  }
+}