zoho giving 414 error

zoho giving 414 error

I am using coldfusion to post a code to the Zoho Invoice API 

So far so good, if i send a very Long Data in JSONString it throws me 414 error: 

Here is the code which i am using 

<cfhttpparam type="header" name="Content-Type" value="application/json">
</cfhttp>

this way: it gives 414 error, if i try to pass JSONString in body without giving and with providing name, it says invalid JSONString like this 

<cfhttpparam type="body"  value="#arguments.jsondata#">

<cfhttpparam type="body" name="JSONString" value="#arguments.jsondata#">

I do not understand if they have provided Method, why not accept the JSONString in body rather than in URL