Fix QLDocs and the qhelp example

Author: atorralba

java/ql/lib/semmle/code/java/frameworks/android/SQLite.qll

@@ -1,3 +1,5 @@
+/** Provides classes and predicates for working with SQLite databases. */
+
 import java
 import Android
 import semmle.code.java.dataflow.FlowSteps
@@ -24,10 +26,16 @@ class TypeDatabaseUtils extends Class {
   TypeDatabaseUtils() { hasQualifiedName("android.database", "DatabaseUtils") }
 }
 
+/**
+ * The class `android.database.sqlite.SQLiteOpenHelper`.
+ */
 class TypeSQLiteOpenHelper extends Class {
   TypeSQLiteOpenHelper() { this.hasQualifiedName("android.database.sqlite", "SQLiteOpenHelper") }
 }
 
+/**
+ * The class `android.database.sqlite.SQLiteStatement`.
+ */
 class TypeSQLiteStatement extends Class {
   TypeSQLiteStatement() { this.hasQualifiedName("android.database.sqlite", "SQLiteStatement") }
 }

java/ql/lib/semmle/code/java/frameworks/android/Widget.qll

@@ -1,3 +1,5 @@
+/** Provides classes and predicates for working with Android widgets. */
+
 import java
 import semmle.code.java.dataflow.ExternalFlow
 import semmle.code.java.dataflow.FlowSources

java/ql/src/Security/CWE/CWE-312/CleartextStorageAndroidDatabase.java

@@ -16,3 +16,12 @@ public void sqlCipherStorageSafe(String name, String password, String databasePa
 		net.sqlcipher.database.SQLiteDatabase.openOrCreateDatabase("test", databasePassword, null);
 	db.execSQL("INSERT INTO users VALUES (?, ?)", new String[] {name, password});
 }
+
+private static String encrypt(String cleartext) {
+    // Use an encryption or strong hashing algorithm in the real world.
+    // The example below just returns a SHA-256 hash.
+    MessageDigest digest = MessageDigest.getInstance("SHA-256");
+    byte[] hash = digest.digest(cleartext.getBytes(StandardCharsets.UTF_8));
+    String encoded = Base64.getEncoder().encodeToString(hash);
+    return encoded;
+}