| Name | Description | Type | Package | Framework |
| Nullable | An immutable object that could be defined as null. | Class | org.apache.poi.openxml4j.util | Apache POI |
| ZipEntrySource | An Interface to make getting the different bits of a Zip File easy. | Interface | org.apache.poi.openxml4j.util | Apache POI |
| ZipFileZipEntrySource | A ZipEntrySource wrapper around a ZipFile. | Class | org.apache.poi.openxml4j.util | Apache POI |
| ZipInputStreamZipEntrySource | Provides a way to get at all the ZipEntries from a ZipInputStream, as many times as required. | Class | org.apache.poi.openxml4j.util | Apache POI |
| ZipInputStreamZipEntrySource .FakeZipEntry | So we can close the real zip entry and still effectively work with it. | Class | org.apache.poi.openxml4j.util.ZipInputStreamZipEntrySource | Apache POI |
| ZipSecureFile | This class wraps a ZipFile in order to check the entries for zip bombs | Class | org.apache.poi.openxml4j.util | Apache POI |
| ZipSecureFile .ThresholdInputStream | Class | org.apache.poi.openxml4j.util.ZipSecureFile | Apache POI | |