public boolean isMultiValuePermitted() {
        if (propertyType == PropertyType.BAG || propertyType == PropertyType.SEQ ||
                propertyType == PropertyType.ALT) {
            return true;
        } else if (propertyType == PropertyType.COMPOSITE) {
            // Base it on the primary property's behaviour
            return primaryProperty.isMultiValuePermitted();
        }
        return false;
    }
Is the PropertyType one which accepts multiple values?
tika-core/src/main/java/org/apache/tika/metadata/Property.java