externalManagedMigrationTestingPercentage property
Determines the fraction of requests that should be processed by the Global external Application Load Balancer.
The value of this field must be in the range [0, 100]. Session affinity options will slightly affect this routing behavior, for more details, see: Session Affinity. This value can only be set if the loadBalancingScheme in the BackendService is set to EXTERNAL (when using the classic Application Load Balancer) and the migration state is TEST_BY_PERCENTAGE.
Implementation
core.double? externalManagedMigrationTestingPercentage;