curl --request POST \
  --url https://api.hubapi.com/conversations/v3/custom-channels/ \
  --header 'Content-Type: application/json' \
  --data '{
  "channelDescription": "<string>",
  "capabilities": "{\"richText\":[\"HYPERLINK\",\"TEXT_ALIGNMENT\",\"BLOCKQUOTE\"],\"threadingModel\":\"DELIVERY_IDENTIFIER | INTEGRATION_THREAD_ID\",\"allowInlineImages\":false,\"allowOutgoingMessages\":false,\"allowConversationStart\":false,\"maxFileAttachmentCount\":1,\"allowMultipleRecipients\":false,\"deliveryIdentifierTypes\":[],\"outgoingAttachmentTypes\":[\"FILE\"],\"maxFileAttachmentSizeBytes\":1500000,\"allowedFileAttachmentMimeTypes\":[\"image/png\"],\"maxTotalFileAttachmentSizeBytes\":1500000}",
  "channelAccountConnectionRedirectUrl": "<string>",
  "channelLogoUrl": "<string>",
  "name": "<string>",
  "webhookUrl": "<string>"
}'

{
  "channelDescription": "<string>",
  "createdAt": "2023-11-07T05:31:56Z",
  "capabilities": "{\"richText\":[\"HYPERLINK\",\"TEXT_ALIGNMENT\",\"BLOCKQUOTE\"],\"threadingModel\":\"DELIVERY_IDENTIFIER | INTEGRATION_THREAD_ID\",\"allowInlineImages\":false,\"allowOutgoingMessages\":false,\"allowConversationStart\":false,\"maxFileAttachmentCount\":1,\"allowMultipleRecipients\":false,\"deliveryIdentifierTypes\":[],\"outgoingAttachmentTypes\":[\"FILE\"],\"maxFileAttachmentSizeBytes\":1500000,\"allowedFileAttachmentMimeTypes\":[\"image/png\"],\"maxTotalFileAttachmentSizeBytes\":1500000}",
  "channelAccountConnectionRedirectUrl": "<string>",
  "channelLogoUrl": "<string>",
  "name": "<string>",
  "id": "<string>",
  "webhookUrl": "<string>"
}