code: func (c *Container) InjectV3MetadataEndpoint() {
  	c.lock.Lock()
  	defer c.lock.Unlock()
  
  	// don't assume that the environment variable map has been initialized by others
  	if c.Environment == nil {
  		c.Environment = make(map[string]string)
  	}
  
  	c.Environment[MetadataURIEnvironmentVariableName] =
  		fmt.Sprintf(MetadataURIFormat, c.V3EndpointID)
  }
docs: // InjectV3MetadataEndpoint injects the v3 metadata endpoint as an environment variable for a container