Migrate Java code to separate QL repo.

java/ql/src/Likely Bugs/Statements/StaticFieldWrittenByInstance.java

@@ -0,0 +1,22 @@
+public class Customer {
+	private static List<Customer> customers;
+	public void initialize() {
+		// AVOID: Static field is written to by instance method.
+		customers = new ArrayList<Customer>();
+		register();
+	}
+	public static void add(Customer c) {
+		customers.add(c);
+	}
+}
+
+// ...
+public class Department {
+	public void addCustomer(String name) {
+		Customer c = new Customer(n);
+		// The following call overwrites the list of customers
+		// stored in 'Customer' (see above).
+		c.initialize();
+		Customer.add(c);
+	}
+}