FULL PRODUCT VERSION :
java version "1.8.0_45"
Java(TM) SE Runtime Environment (build 1.8.0_45-b14)
Java HotSpot(TM) Client VM (build 25.45-b02, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.3.9600]

A DESCRIPTION OF THE PROBLEM :
Bean properties declared as default interface methods, are not available in the list of properties returned by java.beans.Introspector.getBeanInfo(...).getPropertyDescriptors()

see also here: http://stackoverflow.com/questions/23219006/default-method-in-interface-in-java-8-and-bean-info-introspector

In Introspector#getPublicDeclaredMethods(), the following piece of code:

if (!method.getDeclaringClass().equals(clz)) {
    result[i] = null; // ignore methods declared elsewhere
}

should look like this:

if (!method.getDeclaringClass().equals(clz) && !method.getDeclaringClass().isInterface()) {
    result[i] = null; // ignore methods declared elsewhere
}

or be removed completely

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
run the attached test case

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
class, letter
class, letter
ACTUAL -
class
class, letter

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.beans.*;
import java.util.*;
import java.util.stream.*;

public class Bug
{

public static interface Interface {
    default public String getLetter() {
        return "A";
    }
}

public static class ClassA implements Interface {
}

public static class ClassB implements Interface {
    public String getLetter() {
        return "B";
    }
}

public static String formatData(PropertyDescriptor[] pds) {
    return Arrays.asList(pds).stream()
            .map((pd) -> pd.getName()).collect(Collectors.joining(", "));

}

public static void main(String[] args) {
    try {
        System.out.println(
                formatData(Introspector.getBeanInfo(ClassA.class)
                        .getPropertyDescriptors()));
        System.out.println(
                formatData(Introspector.getBeanInfo(ClassB.class)
                        .getPropertyDescriptors()));
    } catch (IntrospectionException e) {
        e.printStackTrace();
    }
}

}
---------- END SOURCE ----------