#84 Work on data layer

layers/src/main/java/com/iluwatar/layers/Cake.java

@@ -0,0 +1,28 @@
+package com.iluwatar.layers;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+import javax.persistence.OneToMany;
+import javax.persistence.OneToOne;
+
+@Entity
+public class Cake {
+
+	@Id
+	@GeneratedValue
+	private Long id;
+	
+	@OneToMany
+	private List<CakeLayer> layers;
+
+	@OneToOne
+	private CakeTopping topping;
+	
+	public Cake() {		
+		layers = new ArrayList<>();
+	}
+}

layers/src/main/java/com/iluwatar/layers/CakeLayer.java

@@ -0,0 +1,25 @@
+package com.iluwatar.layers;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+
+@Entity
+public class CakeLayer {
+
+	@Id
+	@GeneratedValue
+	private Long id;
+
+	private String name;
+
+	private int calories;
+
+	public CakeLayer() {
+	}
+
+	public CakeLayer(String name, int calories) {
+		this.name = name;
+		this.calories = calories;
+	}
+}

layers/src/main/java/com/iluwatar/layers/CakeTopping.java

@@ -0,0 +1,25 @@
+package com.iluwatar.layers;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+
+@Entity
+public class CakeTopping {
+
+	@Id
+	@GeneratedValue
+	private Long id;
+	
+	private String name;
+	
+	private int calories;
+	
+	public CakeTopping() {
+	}
+	
+	public CakeTopping(String name, int calories) {
+		this.name = name;
+		this.calories = calories;
+	}
+}