Using && in complex expression language conditions do not work anymore.
Using the example from https://izpack.atlassian.net/wiki/display/IZPACK/Conditions
ERROR: 'The entity name must immediately follow the '&' in the entity reference.'
ERROR: 'com.sun.org.apache.xml.internal.utils.WrappedRuntimeException: The entity name must immediately follow the '&' in the entity reference.'
The problem is caused by xml parsing in com.izforge.izpack.api.adaptator.impl.XMLParser.parseLineNrFromInputSource(InputSource)
Expressions without and-Condition && do work.
At the moment due to the XML parser it has to be escaped -
because parser expects predefined or manually defined entity name after & character. It works then.
The double ampersand is very unfortunate choice So maybe it would be better to suggest a better operator for "and" just for the sake of XML readability.
This works as designed, or has been forgotten when designing the extended condition expression language.
There is no way around it without changing the syntax of the condition expression language.