Do you not have the ZipFile instance from which the ZipEntry was sourced? If you do you could use ZipFile.getInputStream(ZipEntry).
https://docs.oracle.com/javase/8/docs/api/java/util/zip/ZipFile.html
PS. Just had a quick look at the code and a ZipEntry is not a wrapper for the underlying data in the zip file. It is just a "place holder" for the entry as far as I can see (i.e. zipped file attributes not the data). The actual stream is created through a JNI call in the ZipFile class. Meaning that I do not believe you can do what you are looking to do in a practical way.
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