Begin by setting up webhooks in your Braintree account. Log in to the Braintree Control Panel, navigate to 'Settings', and then 'Webhooks'. Create a new webhook to capture the specific events you are interested in (such as transaction events). This will allow Braintree to send real-time HTTP POST requests to your specified endpoint whenever these events occur.

Create a server-side application to handle incoming HTTP POST requests from Braintree’s webhooks. This can be done using a language of your choice, such as Python, Node.js, or Java. Ensure your server is publicly accessible and can process the JSON payloads sent by Braintree. This application will act as an intermediary to catch events and prepare them for forwarding.

In your webhook receiver, implement logic to parse the JSON payload received from Braintree. Validate the payload to ensure its authenticity and integrity using Braintree's signature verification process. This step is crucial to ensure that the data being processed is actually from Braintree and has not been tampered with.

Once you have validated the payload, transform the data into a format suitable for Google Pub/Sub. This might involve reformatting JSON structures or extracting specific fields that are necessary for your use case. This step ensures that the data is ready for consumption by services or applications subscribing to your Pub/Sub topics.

If you haven’t already, set up Google Cloud Pub/Sub by creating a Google Cloud Platform (GCP) project. Within this project, enable the Pub/Sub API. Then, create a Pub/Sub topic that will serve as the destination for the data coming from Braintree. Note down the topic name, as you will need it for publishing messages.

Authenticate your application to use Google Cloud services. This involves creating a service account in your GCP project with appropriate permissions for Pub/Sub. Download the JSON key file for the service account, and use it in your application to authenticate requests to Google Cloud.

Implement logic in your webhook receiver to publish the transformed Braintree data to your Google Pub/Sub topic. This involves using a client library for Google Cloud Pub/Sub (such as the Python, Node.js, or Java client libraries) to send messages to the topic. Ensure your application handles any potential errors or retries in case of network issues to guarantee reliable data transfer.

By following these steps, you will be able to effectively move data from Braintree to Google Pub/Sub without relying on third-party connectors or integrations.