src/main/java/org/apache/commons/text/StrSubstitutor.java [802:840]:
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        if (!substitute(buf, 0, length)) {
            return false;
        }
        source.replace(offset, offset + length, buf.toString());
        return true;
    }

    /**
     * Replaces all the occurrences of variables within the given source buffer
     * with their matching values from the resolver.
     * The buffer is updated with the result.
     *
     * @param source  the buffer to replace in, updated, null returns zero
     * @return true if altered
     */
    public boolean replaceIn(final StringBuilder source) {
        if (source == null) {
            return false;
        }
        return replaceIn(source, 0, source.length());
    }

    /**
     * Replaces all the occurrences of variables within the given source builder
     * with their matching values from the resolver.
     * The builder is updated with the result.
     * <p>
     * Only the specified portion of the buffer will be processed.
     * The rest of the buffer is not processed, but it is not deleted.
     * </p>
     *
     * @param source  the buffer to replace in, updated, null returns zero
     * @param offset  the start offset within the array, must be valid
     * @param length  the length within the buffer to be processed, must be valid
     * @return true if altered
     */
    public boolean replaceIn(final StringBuilder source, final int offset, final int length) {
        if (source == null) {
            return false;
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src/main/java/org/apache/commons/text/StringSubstitutor.java [1048:1085]:
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        if (!substitute(buf, 0, length)) {
            return false;
        }
        source.replace(offset, offset + length, buf.toString());
        return true;
    }

    /**
     * Replaces all the occurrences of variables within the given source buffer with their matching values from the
     * resolver. The buffer is updated with the result.
     *
     * @param source the buffer to replace in, updated, null returns zero
     * @return true if altered
     */
    public boolean replaceIn(final StringBuilder source) {
        if (source == null) {
            return false;
        }
        return replaceIn(source, 0, source.length());
    }

    /**
     * Replaces all the occurrences of variables within the given source builder with their matching values from the
     * resolver. The builder is updated with the result.
     * <p>
     * Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is
     * not deleted.
     * </p>
     *
     * @param source the buffer to replace in, updated, null returns zero
     * @param offset the start offset within the source, must be valid
     * @param length the length within the source to be processed, must be valid
     * @return true if altered
     * @throws IllegalArgumentException if variable is not found when its allowed to throw exception
     */
    public boolean replaceIn(final StringBuilder source, final int offset, final int length) {
        if (source == null) {
            return false;
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