Array declaration and initialization
You can only declare primitive arrays. Use List for both primitive and non-primitive arrays.
Type (T) operator
This feature is disabled along with the restriction on Java class usage.
instanceof operator
This feature is disabled along with the restriction on Java class usage.
Assignment operator
All external data used in the expression through external property references are read only.
Static and Instance methods
None of the static or instance methods in the Java API are accessible in expressions.
Operators
A leading and trailing space is required for the binary operators, as explained in the Operators section.
Safe Navigation (?.) Operator
The Safe Navigation operator is disabled because PingOne's expression language already attempts safe navigation internally when accessing object properties, except for object literals similar to the Safe Navigation operator (?.). This allows access to child properties against a parent object without errors, even if the parent object is null.

For example, user.address.city returns null if either user or address is null.