JRJdk13Compiler shows theses warnings:
warning: [removal] Integer(int) in Integer has been deprecated and marked for removal value = new java.lang.Integer(1); //$JR_EXPR_ID=1$
Most probably this deprecated syntax (new java.lang.Integer(int)) is used for initialization of Integer variables defined in the report (built-in variables). Could someone please help me how to change that initialization for Integer.valueOf(int)?
This deprecation started on JDK V9. JasperReports library (and JasperServer) are compatible with specific versions of Java, and so if you compiled the report in JDK 8 you'd eliminate this issue.
Potential solutions include:
1. install JDK 8 and configuring your environment to use that rather than 13
2. update the version of JasperReports/Server you're using - assuming the latest libraries are compatible with JDK 13, I'm a few versions behind and so I'm not sure what's compatible with what
3. ignore it for now - this type of deprecated functionality is not likely to cause problems - that type of casting is so widely used, and the integer functionality so basic, that you likely won't have any problems with this. If your project can't tolerate these warnings, you'll have to work through one of the first two options.