The user´s application has an external entity that generates parameters and adds them to the application´s URL. The URL parameters that can contain alphanumeric characters and the % symbol. For example, the URL could become http://host/owui?param=%20. The issue is that if the user were to only copy http://host/owui?param=%2, an internal server error / illegal argument exception is thrown which is undesirable. Instead, the user would like to be able to handle the exception in the application and display an appropriate error message. It´s possible to reproduce the IllegalStateException using the following component showcase URL: http://component-showcase.icefaces.org/component-showcase/showcase.iface?param=%2 which results in:

java.lang.IllegalArgumentException
java.net.URI.create(URI.java:842)
com.icesoft.faces.webapp.http.servlet.ServletRequestResponse$1.servlet(ServletRequestResponse.java:98)
........
java.net.URISyntaxException: Malformed escape pair at index 79: http://component-showcase.icefaces.org/component-showcase/showcase.iface?param=%2
java.net.URI$Parser.fail(URI.java:2809)
java.net.URI$Parser.scanEscape(URI.java:2939)
java.net.URI$Parser.scan(URI.java:2962)