Fix an issue where calling peek on NativeSql caused a ClassCastException

[nakamura-to]

The ClassCastException occurred when executing peek after calling onDuplicateKeyUpdate or onDuplicateKeyIgnore. For example, the ClassCastException occurred in the following code:

var nativeSql = new NativeSql(config);
var d = new Department_();

nativeSql
    .insert(d)
    .values(
        c -> {
            c.value(d.departmentId, 1);
            c.value(d.departmentNo, 60);
            c.value(d.departmentName, "DEVELOPMENT");
            c.value(d.location, "KYOTO");
            c.value(d.version, 2);
        })
    .onDuplicateKeyUpdate()
    .peek(System.out::println)
    .execute();