You can create filters to your callback Webhooks, If at least 1 Callback Filter is defined, the only Webhooks that will be executed are the Webhooks that match your filters. Everything else will still be created and available for retrieval but their respective HTTPs calls won't be executed.
In the Dev Portal, go to: API Key, scroll until Callback filter then click on Add new Rule:
Fill the name and set your rules.
Name: callback type equals session opened;
Rule Sample Data: you can test your json if the rules matches with the json;
Param One: type;
Operator: Equals (==);
Param Two: session_opened;
if the Rule Sample Data is set you can click on Test Rule, if the rule matches with the json just click on Save Button.
In this case all rules must match (AND case), but you can change to (OR case) as well.
Param One: type;
Operator: Equals (==);
Param Two: container;
AND
Param One: container.state;
Operator: Equals (==);
Param Two: sent;
AND
Param One: container.page_type;
Operator: Different (!=);
Param Two: pushpull;
Param One: type;
Operator: Equals (==);
Param Two: container;
AND
Param One: container.state;
Operator: Equals (==);
Param Two: send;
OR
Param One: container.state;
Operator: Equals (==);
Param Two: sent;