Need help on passing variables to a .exec. See below example.

Can someone help me understand how to pass a a var

val conn_str = "jdbc:postgresql://SomeDatabase/xyz?ssl=true&sslfactory=org.postgresql.ssl.NonValidatingFactory&user=password&user=password"

val conn = DriverManager.getConnection(conn_str)

val statement = conn.createStatement(ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_UPDATABLE)

val scn = scenario("TGT_AddTrip")

  .exec(sessionFunction = (s: Session) => {
    val getUsername = jdbcFeeder("jdbc:postgresql://somedatabase/xyz?ssl=true&sslfactory=org.postgresql.ssl.NonValidatingFactory",
      "user", "password",
      "select Distinct username from users u JOIN contacts c using(contact_id) where c.first_name like 'DriverFirstNameTest_%'")

    var it = getUsername.records.iterator
    var element =
    var Username = element.get("username").get

    println("Username = " + Username)


//Now I want to use the value for "Username" from above in the next section. But when I do it errors

      .body(StringBody("""username=+ Username + &password=1"""))