Resolve "Diamond kata"

Closes #114 (closed)

java-diamond/src/main/java/fr/craft/kata/Diamond.java

+package fr.craft.kata;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.function.IntFunction;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+public class Diamond {
+
+  public static List<String> of(char size) {
+    List<String> diamond = IntStream
+        .range((int) 'A', ((int) size) + 1)
+        .mapToObj(toLine(size))
+        .collect(Collectors.toList());
+
+    List<String> secondPart = new ArrayList<>(diamond);
+    Collections.reverse(secondPart);
+    secondPart.remove(0);
+
+    diamond.addAll(secondPart);
+
+    return diamond;
+  }
+
+  private static IntFunction<String> toLine(char size) {
+    return current -> Line.of((char) current, size)
+        .representation();
+  }
+
+}