JDK-8034802 re-implemented ZipFileSystem.sync(). The new implementation creates a separate OutputStream object (EntryOutputStreamCRC32 or EntryOutputStreamDef) for each entry. For a JAR file with large number of entries, this causes many short lived objects being created. The older version of ZipFileSystem.sync() does not seem to use a separate resource for each entry in the deflated case:

-  if (e.bytes != null) {        // in-memory, deflated
-      os.write(e.bytes);        // already
-      written += e.bytes.length;
-  } else if (e.file != null) {  // tmp file
...
-  }
+  written += writeEntry(e, os, buf); <<<<<<<