spring - Constant meaning in java

Question

Currently, I am developing a spring-boot application and one of the rest controllers looks as follows:

@RequestMapping(value = VALUE)
public class SomeControllerClass {

  public final static String VALUE = UUID.randomUUID().toString();
  
  ...

}

While developing this, I have encountered this issue when setting VALUE for @RequestMapping

Attribute value must be constant

However, if I alter the static field assignment as it's presented below everything works fine:

public final static String VALUE = "someValue";

Now, I am wondering what are the differences (in terms of java constant meaning) between:

public final static String VALUE = "someValue";

and public final static String VALUE = UUID.randomUUID().toString()

Answer 1

I think the formal definition of a constant is section 15.29 (Constant Expressions) in the Java Language Specification:

https://docs.oracle.com/javase/specs/jls/se15/html/jls-15.html#jls-15.29

So, in the case of String constants, it's literal strings and any simple expression that uses other constant String variables.