So Jersey decoding specification is https://github.com/eclipse-ee4j/jersey/blob/2.46/core-common/src/main/java/org/glassfish/jersey/uri/UriComponent.java#L429 and consider that "+" is to be replaced as white space only in query parameters, but not in the path (which is the current use case). Nothing in the code suggest that it can be configured, so I'm afraid it's going to be hard to keep supporting + in REST URLs...
