The CEN header field "external file attributes" holds the Unix file type in the leading 4 bits, but this is not inquired by ZipFileSystem when ZipFileSystem.isSymbolicLink is called. Instead ZipFileSystem always returns false for this method.

A ZIP file with a symbolic link can be created using Info-ZIP as follows:

% touch source
% ln -s source target
% zip -y symlink.zip source target

Here, the source file will have a Unix "external file attribute" of 0x81A4, while the target file has the value 0xA1ED, meaning leading 4 bits "1000" (regular file) vs "1010" (symbolic link).

The solution is to update ZipFileSystem.Entry.isSymbolicLink to compare the leading 4 bits of posixPerms against 012.