#355 document, abstract base, traits and example domain

abstract-document/src/main/java/com/iluwatar/abstractdocument/domain/HasPrice.java

@@ -0,0 +1,13 @@
+package com.iluwatar.abstractdocument.domain;
+
+import java.util.Optional;
+
+import com.iluwatar.abstractdocument.Document;
+
+public interface HasPrice extends Document {
+	
+	default Optional<Number> getPartner() {
+		return Optional.ofNullable((Number) get("price"));
+	}
+
+}