public ProxyConfiguration proxyUsername(String proxyUsername) {
        setProxyUsername(proxyUsername);
        return this;
    }
Sets the optional proxy user name to use if connecting through a proxy.

@param proxyUsername The proxy user name to use if connecting through a proxy.
@return This object for method chaining.
aws-java-sdk-opensdk/src/main/java/com/amazonaws/opensdk/config/ProxyConfiguration.java