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## Description


## Motivation and Context


## How to test this PR?


## Types of changes

     * Prefix used to identify regex patterns in related content terms.
     * When a term starts with this prefix, it is treated as a regular expression
     * pattern rather than an exact match term.
     */
    protected String regexPrefix = "regex:";

    /**
     * Placeholder string used in regex-based related content templates.
     * This placeholder is replaced with the actual search query when
     * a regex pattern matches the query.

 * for any {@link Object}. Also offers basic text processing methods based on this function.
 * Implementations are strongly encouraged to be side-effect-free and immutable.
 *
 * <p>Throughout the documentation of this class, the phrase "matching character" is used to mean
 * "any {@code char} value {@code c} for which {@code this.matches(c)} returns {@code true}".
 *
 * <p><b>Warning:</b> This class deals only with {@code char} values, that is, <a