As part of the fix for JDK-8284371, there was an unintentional change which reverted the reworking of (7) deflate.c undo (6), replaced withe the official zlib repo fix see#305/#f969409

This patch restores that change which is:

git diff
diff --git a/src/java.base/share/native/libzip/zlib/deflate.c b/src/java.base/share/native/libzip/zlib/deflate.c
index ba1f386e5fc..2b80a735886 100644
--- a/src/java.base/share/native/libzip/zlib/deflate.c
+++ b/src/java.base/share/native/libzip/zlib/deflate.c
@@ -555,7 +555,7 @@ int ZEXPORT deflateResetKeep (strm)
         s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
 #endif
         adler32(0L, Z_NULL, 0);
- s->last_flush = Z_NO_FLUSH;
+ s->last_flush = -2;
 
     _tr_init(s);
 
@@ -649,7 +649,7 @@ int ZEXPORT deflateParams(strm, level, strategy)
     func = configuration_table[s->level].func;
 
     if ((strategy != s->strategy || func != configuration_table[level].func) &&
- s->high_water) {
+ s->last_flush != -2) {
         /* Flush the last buffer: */
         int err = deflate(strm, Z_BLOCK);
         if (err == Z_STREAM_ERROR)
 %