Summary
-------

Correct `java.nio.CharBuffer.getChars(int,int,char[],int)` so that it adheres to the class level specification

> This class implements the CharSequence interface so that character
> buffers may be used wherever character sequences are accepted, for
> example in the regular-expression package java.util.regex. The methods
> defined by CharSequence operate relative to the current position of
> the buffer when they are invoked.

Problem
-------
`CharBuffer.getChars` was added in JDK 25 but failed to follow the specification in the class description that implemented `CharSequence` methods are relative to the buffer's current position and not absolute.

Solution
--------

Correct `CharBuffer.getChars` such that the index parameters referring to the buffer are interpreted as relative to the current buffer position and not as absolute positions.

Specification
-------------

    --- a/src/java.base/share/classes/java/nio/X-Buffer.java.template
    +++ b/src/java.base/share/classes/java/nio/X-Buffer.java.template
    @@ -1897,21 +1897,31 @@ public abstract sealed class $Type$Buffer
     #if[char]
     
         /**
    -     * Absolute bulk <i>get</i> method.
    +     * Relative bulk <i>get</i> method.
          *
          * <p> This method transfers {@code srcEnd-srcBegin} characters from this
    -     * buffer into the given array, starting at index {@code srcBegin} in this
    -     * buffer and at offset {@code dstBegin} in the array. The position of this
    -     * buffer is unchanged.
    +     * buffer into the given array, starting at index
    +     * {@code position() + srcBegin} in this buffer and at offset
    +     * {@code dstBegin} in the array. The position of this buffer is unchanged.
    +     *
    +     * <p> An invocation of this method behaves exactly the same was as the
    +     * invocation
    +     *
    +     * {@snippet lang=java :
    +     *     get(position() + srcBegin, dst, dstBegin, srcEnd - srcBegin)
    +     * }
          *
          * @param  srcBegin
    -     *         The index in this buffer from which the first character will be
    -     *         read; must be non-negative and less than {@code limit()}
    +     *         The index in this buffer, relative to the current position,
    +     *         of the first character to
    +     *         read; must be non-negative and less than
    +     *         {@code limit() - position()}
          *
          * @param  srcEnd
    -     *         The index in this buffer directly before the last character to
    -     *         read; must be non-negative and less or equal than {@code limit()}
    -     *         and must be greater or equal than {@code srcBegin}
    +     *         The index in this buffer, relative to the current position,
    +     *         after the last character to read;
    +     *         must be greater than or equal to {@code srcBegin} and less than
    +     *         or equal to {@code limit() - position()}
          *
          * @param  dst
          *         The destination array
    @@ -1924,14 +1934,11 @@ public abstract sealed class $Type$Buffer
          *          If the preconditions on the {@code srcBegin}, {@code srcEnd},
          *          and {@code dstBegin} parameters do not hold
          *
    -     * @implSpec This method is equivalent to
    -     *           {@code get(srcBegin, dst, dstBegin, srcEnd - srcBegin)}.
    -     *
          * @since 25
          */