I have tried to follow this documentation in the most precise way I could:
https://beam.apache.org/documentation/sdks/javadoc/2.0.0/org/apache/beam/sdk/io/xml/XmlIO.html
XmlIO.Read PTransform doesn't support providing multiple record elements (author, title, genre, etc). You have to provide a single root element and a record element and your XML document has to contain records that have the same record element. See the example given in the following location.
https://github.com/apache/beam/blob/master/sdks/java/io/xml/src/main/java/org/apache/beam/sdk/io/xml/XmlIO.java#L59