That's closely related to JDK-8131342 (just a sub-issue).

Please run:

public class EnumTest {

    public class Bean {

        private int a;
        private int b;

        @BeanProperty(description = "A DESCRIPTION")
        public void setA(int v) { a = v; }
        public int getA() { return a; }

        @BeanProperty(description = "B DESCRIPTION")
        public void setB(int v) { b = v; }
        public double getB() { return b; }
    }

    static void printSz(PropertyDescriptor d) {
        Object en = d.getValue("enumerationValues");
        if (en == null) { System.out.println("null enumeration"); } else {
            Object tmp[] = (Object []) en;
            System.out.println("enumeration array size: " + tmp.length);
        }
    }


    public static void main(String[] args) throws Exception {

        BeanInfo i = Introspector.getBeanInfo(Bean.class, Object.class);
        PropertyDescriptor[] ds = i.getPropertyDescriptors();
        for (PropertyDescriptor d: ds) {
            System.out.println(d.getName());
            printSz(d);
        }
    }
}


Output:
a
enumeration array size: 0
b
null enumeration


then please comment out @BeanProperty for "a"; the output:
a
null enumeration
b
null enumeration


if comment out @BeanProperty for "b" (and uncomment for "a"), then the output again looks like as in the initial case:
a
enumeration array size: 0
b
null enumeration


if case of absent annotations:
a
null enumeration
b
null enumeration




Checked with JDK9 b72; Win 7