#355 document, abstract base, traits and example domain

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

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+package com.iluwatar.abstractdocument.domain;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import com.iluwatar.abstractdocument.AbstractDocument;
+
+public class Car extends AbstractDocument implements HasModel, HasPrice, HasParts {
+
+	protected Car() {
+		super(new HashMap<String, Object>());
+	}
+	
+	protected Car(Map<String,Object> properties) {
+		super(properties);
+	}
+
+}

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

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+package com.iluwatar.abstractdocument.domain;
+
+import java.util.Optional;
+
+import com.iluwatar.abstractdocument.Document;
+
+public interface HasModel extends Document {
+	
+	default Optional<String> getModel() {
+		return Optional.ofNullable((String) get("model"));
+	}
+
+}

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

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+package com.iluwatar.abstractdocument.domain;
+
+import java.util.stream.Stream;
+
+import com.iluwatar.abstractdocument.Document;
+
+public interface HasParts extends Document {
+	
+	default Stream<Part> getParts() {
+		return children("parts", Part::new);
+	}
+
+}

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

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+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"));
+	}
+
+}

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

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+package com.iluwatar.abstractdocument.domain;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import com.iluwatar.abstractdocument.AbstractDocument;
+
+public class Part extends AbstractDocument implements HasModel, HasPrice {
+
+	protected Part() {
+		super(new HashMap<String, Object>());
+	}
+	
+	protected Part(Map<String, Object> properties) {
+		super(properties);
+	}
+
+}