gen.writeStartObject();
gen.writeStringField('organizationId', '*********');
gen.writeStringField('deploymentId', '*************');
gen.writeStringField('buttonId', '**********');
gen.writeStringField('sessionId', '18c52-');
gen.writeStringField('userAgent', '');
gen.writeStringField('language', 'en-US');
gen.writeStringField('screenResolution', '1366x768');
gen.writeStringField('visitorName', 'Arun');
gen.writeFieldName('prechatDetails');
    gen.writeStartArray();
    gen.writeEndArray();
gen.writeFieldName('prechatEntities');
    gen.writeStartArray();
    gen.writeEndArray();
gen.writeBooleanField('receiveQueueUpdates', true);
gen.writeBooleanField('isPost', true);
gen.writeEndObject();