Described here:
https://mail.openjdk.java.net/pipermail/beans-dev/2019-March/000405.html

The behavior of PropertyDescription.getReadMethod has been changed for boolean properties. Previously (for 8), the "is" getter was used when both "is"/"get" getters provided. However now (since 9), the "get" getter is used in this case.

It violates the JavaBeans API spec, quotation from the spec - This "is<PropertyName>" method may be provided instead of a "get<PropertyName>" method, or it may be provided in addition to a "get<PropertyName>" method. In either case, if the "is<PropertyName>" method is present for a boolean property then we will use the "is<PropertyName>" method to read the property value.