private void ensureNameIsValid(String name) {
            if (!NAME_PATTERN.matcher(name).matches()) {
                throw error(String.format("Invalid format expression name `%s`", name));
            }
        }
A BlockOperation that repeats a template for each value referenced by the block. Each iteration pushes
a state to the writer that includes key, value, key.first, and key.last context properties. The name
of the context property can be customized in the template.
smithy-utils/src/main/java/software/amazon/smithy/utils/CodeFormatter.java