public static CallCredentials bearerAuth(final Supplier<String> tokenSource) {
        return authorizationHeader(() -> BEARER_AUTH_PREFIX + tokenSource.get());
    }
Creates new call credentials with the given token source for bearer auth. Use this method if you derive the token
from the active context (e.g. currently logged in user) or dynamically obtain it from the authentication server.

<p>
<b>Note:</b> This method uses experimental grpc-java-API features.
</p>

@param tokenSource the bearer token source to use
@return The newly created bearer auth credentials.
@see SecurityConstants#BEARER_AUTH_PREFIX
@see #authorizationHeader(Supplier)
grpc-client-spring-boot-starter/src/main/java/net/devh/boot/grpc/client/security/CallCredentialsHelper.java