rest-assured/src/main/java/io/restassured/builder/RequestSpecBuilder.java
public RequestSpecBuilder addFormParam(String parameterName, Collection<?> parameterValues) {
        spec.formParam(parameterName, parameterValues);
        return this;
    }
public RequestSpecBuilder addFormParam(String parameterName, Collection<?> parameterValues) {
        spec.formParam(parameterName, parameterValues);
        return this;
    }
public RequestSpecBuilder addFormParam ( String parameterName , Collection < ? > parameterValues ) { spec . formParam ( parameterName , parameterValues ) ; return this ; }
Add a form parameter to be sent with the request. This method is the same as {@link #addParam(String, java.util.Collection)}
for all HTTP methods except PUT where this method can be used to differentiate between form and query params.

@param parameterName   The parameter key
@param parameterValues The parameter values
@return The request specification builder
@see #addFormParam(String, Object...)
Add a form parameter to be sent with the request . This method is the same as { @link #addParam ( String java . util . Collection ) } for all HTTP methods except PUT where this method can be used to differentiate between form and query params .