RFR: 8358623: Avoid unnecessary data copying in ICC_Profile [v2]

[Phil Race]

On Fri, 13 Jun 2025 20:24:49 GMT, Sergey Bylokhov <serb at openjdk.org> wrote:

>> This PR simplifies several aspects of the ICC_Profile class:
>> 
>> - [Change 1](https://github.com/openjdk/jdk/pull/25650/commits/426a608b1df9e39e221d05e7374a3fecf6e6cf30):
>>     The ICC_Profile.getInstance(byte[] data) method used to copy the profile header for validation. This copy appears redundant, as the original data array is used later anyway. This logic was originally introduced by [JDK-8347377](https://bugs.openjdk.org/browse/JDK-8347377).
>> 
>> - [Change 2](https://github.com/openjdk/jdk/pull/25650/commits/4035c8b1f7e1dcbc9941ead939218bba47b0a2fe):
>>     In some places, the code retrieves the profile header using getData(icSigHead), which always creates a new array. It is now replaced with private getData(cmmProfile(), icSigHead) to avoid unnecessary copying. To clarify the purpose of the private method, I have added documentation.
>> 
>>  - [Change 3](https://github.com/openjdk/jdk/pull/25650/commits/96ad456593de3dd68c3ae6840fffee7bac68bc0c):
>> After Change 2, static analysis tools began reporting a potential NPE when using getData(cmmProfile(), icSigHead), since it may return null. To address this, the internal implementation of getData was updated to always return a non-null value or throw an exception. The public method now catches this exception and returns null, as required by the specification. **Note**: this potential NPE is not a regression introduced by any changes, it simply became easier for tools to detect due to the simplified code.
>> 
>> @prrace @honkar-jdk please take a look
>
> Sergey Bylokhov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   theHeader -> data

This looks OK to me.  I see @honkar-jdk says CI testing has already been done.

-------------

Marked as reviewed by prr (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/25650#pullrequestreview-2984867185