add solutions for hw7 (markup) and tests

java/markup/Emphasis.java

@@ -0,0 +1,24 @@
+package markup;
+
+import java.util.List;
+
+public class Emphasis extends AbstractMarkup {
+    public Emphasis(List<MarkupElement> elements) {
+        super(elements);
+    }
+
+    @Override
+    public void toMarkdown(StringBuilder sb) {
+        toMarkdown(sb, "*");
+    }
+
+    @Override
+    public void toHtml(StringBuilder sb) {
+        toHtml(sb, "em");
+    }
+
+    @Override
+    public void toTex(StringBuilder sb) {
+        toTex(sb, "\\emph");
+    }
+}