src/main/java/org/apache/commons/text/StrBuilder.java [2749:2859]:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
        if (nullText != null && nullText.isEmpty()) {
            nullText = null;
        }
        this.nullText = nullText;
        return this;
    }

    /**
     * Gets the length of the string builder.
     * <p>
     * This method is the same as {@link #length()} and is provided to match the API of Collections.
     * </p>
     *
     * @return The length
     */
    public int size() {
        return size;
    }

    /**
     * Checks whether this builder starts with the specified string.
     * <p>
     * Note that this method handles null input quietly, unlike String.
     * </p>
     *
     * @param str the string to search for, null returns false
     * @return true if the builder starts with the string
     */
    public boolean startsWith(final String str) {
        if (str == null) {
            return false;
        }
        final int len = str.length();
        if (len == 0) {
            return true;
        }
        if (len > size) {
            return false;
        }
        for (int i = 0; i < len; i++) {
            if (buffer[i] != str.charAt(i)) {
                return false;
            }
        }
        return true;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public CharSequence subSequence(final int startIndex, final int endIndex) {
        if (startIndex < 0) {
            throw new StringIndexOutOfBoundsException(startIndex);
        }
        if (endIndex > size) {
            throw new StringIndexOutOfBoundsException(endIndex);
        }
        if (startIndex > endIndex) {
            throw new StringIndexOutOfBoundsException(endIndex - startIndex);
        }
        return substring(startIndex, endIndex);
    }

    /**
     * Extracts a portion of this string builder as a string.
     *
     * @param start the start index, inclusive, must be valid
     * @return The new string
     * @throws IndexOutOfBoundsException if the index is invalid
     */
    public String substring(final int start) {
        return substring(start, size);
    }

    /**
     * Extracts a portion of this string builder as a string.
     * <p>
     * Note: This method treats an endIndex greater than the length of the builder as equal to the length of the builder, and continues without error, unlike
     * StringBuffer or String.
     *
     * @param startIndex the start index, inclusive, must be valid
     * @param endIndex   the end index, exclusive, must be valid except that if too large it is treated as end of string
     * @return The new string
     * @throws IndexOutOfBoundsException if the index is invalid
     */
    public String substring(final int startIndex, int endIndex) {
        endIndex = validateRange(startIndex, endIndex);
        return new String(buffer, startIndex, endIndex - startIndex);
    }

    /**
     * Copies the builder's character array into a new character array.
     *
     * @return a new array that represents the contents of the builder
     */
    public char[] toCharArray() {
        return size == 0 ? ArrayUtils.EMPTY_CHAR_ARRAY : Arrays.copyOf(buffer, size);
    }

    /**
     * Copies part of the builder's character array into a new character array.
     *
     * @param startIndex the start index, inclusive, must be valid
     * @param endIndex   the end index, exclusive, must be valid except that if too large it is treated as end of string
     * @return a new array that holds part of the contents of the builder
     * @throws IndexOutOfBoundsException if startIndex is invalid, or if endIndex is invalid (but endIndex greater than size is valid)
     */
    public char[] toCharArray(final int startIndex, int endIndex) {
        endIndex = validateRange(startIndex, endIndex);
        final int len = endIndex - startIndex;
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -



src/main/java/org/apache/commons/text/TextStringBuilder.java [3034:3146]:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
        if (nullText != null && nullText.isEmpty()) {
            nullText = null;
        }
        this.nullText = nullText;
        return this;
    }

    /**
     * Gets the length of the string builder.
     * <p>
     * This method is the same as {@link #length()} and is provided to match the API of Collections.
     * </p>
     *
     * @return The length
     */
    public int size() {
        return size;
    }

    /**
     * Checks whether this builder starts with the specified string.
     * <p>
     * Note that this method handles null input quietly, unlike String.
     * </p>
     *
     * @param str the string to search for, null returns false
     * @return true if the builder starts with the string
     */
    public boolean startsWith(final String str) {
        if (str == null) {
            return false;
        }
        final int len = str.length();
        if (len == 0) {
            return true;
        }
        if (len > size) {
            return false;
        }
        for (int i = 0; i < len; i++) {
            if (buffer[i] != str.charAt(i)) {
                return false;
            }
        }
        return true;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public CharSequence subSequence(final int startIndex, final int endIndex) {
        if (startIndex < 0) {
            throw new StringIndexOutOfBoundsException(startIndex);
        }
        if (endIndex > size) {
            throw new StringIndexOutOfBoundsException(endIndex);
        }
        if (startIndex > endIndex) {
            throw new StringIndexOutOfBoundsException(endIndex - startIndex);
        }
        return substring(startIndex, endIndex);
    }

    /**
     * Extracts a portion of this string builder as a string.
     *
     * @param start the start index, inclusive, must be valid
     * @return The new string
     * @throws IndexOutOfBoundsException if the index is invalid
     */
    public String substring(final int start) {
        return substring(start, size);
    }

    /**
     * Extracts a portion of this string builder as a string.
     * <p>
     * Note: This method treats an endIndex greater than the length of the builder as equal to the length of the
     * builder, and continues without error, unlike StringBuffer or String.
     * </p>
     *
     * @param startIndex the start index, inclusive, must be valid
     * @param endIndex the end index, exclusive, must be valid except that if too large it is treated as end of string
     * @return The new string
     * @throws IndexOutOfBoundsException if the index is invalid
     */
    public String substring(final int startIndex, int endIndex) {
        endIndex = validateRange(startIndex, endIndex);
        return new String(buffer, startIndex, endIndex - startIndex);
    }

    /**
     * Copies the builder's character array into a new character array.
     *
     * @return a new array that represents the contents of the builder
     */
    public char[] toCharArray() {
        return size == 0 ? ArrayUtils.EMPTY_CHAR_ARRAY : Arrays.copyOf(buffer, size);
    }

    /**
     * Copies part of the builder's character array into a new character array.
     *
     * @param startIndex the start index, inclusive, must be valid
     * @param endIndex the end index, exclusive, must be valid except that if too large it is treated as end of string
     * @return a new array that holds part of the contents of the builder
     * @throws IndexOutOfBoundsException if startIndex is invalid, or if endIndex is invalid (but endIndex greater than
     *         size is valid)
     */
    public char[] toCharArray(final int startIndex, int endIndex) {
        endIndex = validateRange(startIndex, endIndex);
        final int len = endIndex - startIndex;
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -