FhirTerser cannot clone extensions

[Virdulys]

    @Test
    public void testTerser() {
        Patient patient = new Patient();

        patient.addUndeclaredExtension(new ExtensionDt(false, "blahblah"));

        new FhirTerser(FhirContext.forDstu1()).cloneInto(patient, new Patient(), false);
    }

FhirTerser:151 causes exception to be thrown if we use it to clone extension, no matter if extension is in root or child in RuntimeChildChoiceDefinition.java:78, because the passed parameter value is simply "extension". Is this by design and am I doing something wrong? The same is happening when using xmlParser, when parsing to and from string.

[jamesagnew]

Thanks for the report, and for providing a test case!

I'll check in a fix shortly.