public String getStringMemberOrDefault(String memberName, String defaultValue) {
        return getStringMember(memberName).map(StringNode::getValue).orElse(defaultValue);
    }
Gets the member with the given name, and if present, expects it to
be a string, otherwise returns the default value.

@param memberName Name of the member to get.
@param defaultValue Default string value to return if the member is not present.
@return Returns a String value contained in the String node or the default value.
@throws ExpectationNotMetException if the member is not a string.
smithy-model/src/main/java/software/amazon/smithy/model/node/ObjectNode.java