@SuppressWarnings("unchecked")
        public BUILDER addValue(String value) {
            values.get().add(Objects.requireNonNull(value));
            return (BUILDER) this;
        }
Adds a value to the builder.

@param value Value to add.
@return Returns the builder.
smithy-model/src/main/java/software/amazon/smithy/model/traits/StringListTrait.java