Norconex Importer is a Java library and command-line application meant to "parse" and "extract" content out of a file as plain text, whatever its format (HTML, PDF, Word, etc). In addition, it allows you to perform any manipulation on the extracted text before using it in your own service or application.
DOMPreserveTransformer was added in v3.0.1. This is noted in the Javadocs (link) and it's release notes (link).
Please use Importer 3.0.1-SNAPSHOT release.
I already install all the importer classes by downloading them but still, it shows the error. If someone has any idea then please help asap
Note: I am using Norconex version 3.0. also, the importers are also in v3