public PropertiesEndpointGroupBuilder defaultPort(int defaultPort) {
        checkArgument(defaultPort > 0 && defaultPort <= 65535,
                      "defaultPort: %s (expected: 1-65535)", defaultPort);
        this.defaultPort = defaultPort;
        return this;
    }
Sets the default port number which is used when parsing an {@link Endpoint} without a port number.
core/src/main/java/com/linecorp/armeria/client/endpoint/PropertiesEndpointGroupBuilder.java