public ImmutableMapParameter<K, V> build() {
            HashMap<K, V> builtMap = new HashMap<K, V>();
            builtMap.putAll(entries);
            return new ImmutableMapParameter<K, V>(builtMap);
        }
Generates and returns a new ImmutableMapParameter instance which
contains all the entries added into the Builder by {@code put()}
method.
aws-java-sdk-core/src/main/java/com/amazonaws/util/ImmutableMapParameter.java