add some comments.

src/main/java/de/neemann/digital/builder/circuit/FragmentSameInValue.java

@@ -10,12 +10,20 @@ import java.util.List;
 import static de.neemann.digital.draw.shapes.GenericShape.SIZE;
 
 /**
+ * Takes a fragment ans sets all inputs to a single value.
+ * Used to create a circuit with a JK ff with J==K.
+ *
  * @author hneemann
  */
 public class FragmentSameInValue implements Fragment {
     private final Fragment fragment;
     private Vector pos;
 
+    /**
+     * Creates a new instance
+     *
+     * @param fragment the fragment with all imputs are the same value
+     */
     public FragmentSameInValue(Fragment fragment) {
         this.fragment = fragment;
     }

src/main/java/de/neemann/digital/builder/circuit/FragmentVisualElement.java

@@ -60,7 +60,7 @@ public class FragmentVisualElement implements Fragment {
     }
 
     /**
-     * Used to ignore the c input at the JK flipflop
+     * Used to ignore the c input at a JK flipflop
      *
      * @param n number of pin to ignore
      * @return this for call chaining
@@ -75,7 +75,7 @@ public class FragmentVisualElement implements Fragment {
      *
      * @param key     the key
      * @param value   the value
-     * @param <VALUE> the tyype of the value
+     * @param <VALUE> the type of the value
      * @return this for call chaining
      */
     public <VALUE> FragmentVisualElement setAttr(Key<VALUE> key, VALUE value) {