public void setReuseLastProvider(boolean b) {
        this.reuseLastProvider = b;
    }
Enables or disables caching of the last successful credentials provider
in this chain. Reusing the last successful credentials provider will
typically return credentials faster than searching through the chain.

@param b
           Whether to enable or disable reusing the last successful
           credentials provider for future credentials requests instead
           of searching through the whole chain.
aws-java-sdk-core/src/main/java/com/amazonaws/auth/AWSCredentialsProviderChain.java