docs: add Alibaba attribution to legacy-derived files in fesod-sheet

[skytin1004]

Purpose of the pull request

Related: #878

This PR adds the Alibaba attribution block to 6 fesod-sheet files that appear to be legacy EasyExcel-derived or legacy-derived files.

What's changed?

I reviewed the Java files in fesod-sheet and checked the remaining ASF-only files against git history, prior refactor commits, and existing files that already keep Alibaba attribution.

I scanned attribution across the module

• 469 Java files in fesod-sheet
• 412 files already had ASF + Alibaba headers
• 57 files had ASF-only headers
• 0 files were missing ASF headers

Based on that review, I identified 6 files with clear evidence of derivation from legacy EasyExcel code or legacy-derived test data, and added the required Alibaba attribution block after the ASF license header:

• FesodSheet.java
• FastExcel.java
• FastExcelFactory.java
• MaxHeadSizeData.java
• HiddenSheetsData.java
• WriteSheetData.java

I selected these files conservatively based on the following evidence:

• FesodSheet.java traces back to the legacy core API (EasyExcel.java / EasyExcelFactory.java) via git log --follow
• FastExcel.java is part of the EasyExcel-to-FastExcel compatibility/rename path and retained as a deprecated alias
• FastExcelFactory.java follows the same legacy factory path and is kept as a deprecated compatibility alias
• MaxHeadSizeData.java was copied from ComplexHeadData.java, which already retains Alibaba attribution
• HiddenSheetsData.java was copied from MultipleSheetsData.java, which already retains Alibaba attribution
• WriteSheetData.java was copied from NoHeadData.java, which already retains Alibaba attribution

I intentionally kept this PR narrow and did not update the other remaining ASF-only files in fesod-sheet, because their introduction commits indicate they are FastExcel/Fesod-added feature, bugfix, fuzz, or unit-test files.

Checklist

• I have read the Contributor Guide.
• I have written the necessary doc or comment.
• I have added the necessary unit tests and all cases have passed.

[delei]

Hi, @skytin1004

FYI, FastExcel, FastExcelFactory, and FesodSheet are not derived from Alibaba's EasyExcel.

[skytin1004]

Thanks @delei for the clarification.

I've removed the attribution blocks from FastExcel.java, FastExcelFactory.java, and FesodSheet.java.

For the remaining three files, I kept the attribution based on their copy history from existing files that already retain Alibaba attribution:

• MaxHeadSizeData.java: copied from ComplexHeadData.java in 8ad28c2
• HiddenSheetsData.java: copied from MultipleSheetsData.java in 1088d68
• WriteSheetData.java: copied from NoHeadData.java in 07582a0

If these should also be treated as FastExcel/Fesod-added files, I'm happy to update them accordingly.

[bengbengbalabalabeng]

AFAIK, all of these files were added during the FastExcel/Fesod development phase and were not derived from Alibaba EasyExcel.

• MaxHeadSizeData.java originates from PR #287
• HiddenSheetsData.java originates from PR #354
• WriteSheetData.java originates from PR #411

Their design purpose and implementation scope differ significantly from the EasyExcel test/demo classes mentioned in the discussion.

Additionally, MaxHeadSizeData.java and the EasyExcel classes com.alibaba.easyexcel.test.core.head.ComplexHeadData.java / com.alibaba.easyexcel.test.demo.write.ComplexHeadData.java are fundamentally different in content.

Therefore, IMO these files do not require additional Alibaba copyright statement.

[skytin1004]

Hi @bengbengbalabalabeng
Thanks for the clarification, this is very helpful.

Since these files are not derived from EasyExcel, I'll go ahead and close this PR.

Please feel free to reopen or let me know if I missed anything.