Statement.ececuteUpdate() closes ResultSet obtained from same Statement

I am not sure if this is a bug or a feature, but here it goes:

package cpssd.postgresql;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.sql.*;

public class TicketIT {

private static Connection getConnection() throws SQLException {
return DriverManager.getConnection("jdbc:postgresql:postgres");
}

@Before
public void createTable() throws SQLException {
try (Connection c = getConnection();
Statement s = c.createStatement()) {
s.executeUpdate("CREATE TABLE test(a INT)");
}
}

@After
public void dropTable() throws SQLException {
try (Connection c = getConnection();
Statement s = c.createStatement()) {
s.executeUpdate("DROP TABLE test");
}
}

@Test(expected = SQLException.class)
public void testSharedStatementClosesResultSet() throws SQLException {
try (Connection c = getConnection();
Statement s = c.createStatement()) {
try (ResultSet rs = s.executeQuery("SELECT a FROM test")) {
s.executeUpdate("INSERT INTO test(a) VALUES (1)");
// Expected false, but throws SQLException: This statement has been closed.
assert !rs.next();
}
}
}

@Test
public void testUsingAnotherStatementWorks() throws SQLException {
try (Connection c = getConnection();
Statement s1 = c.createStatement()) {
try (ResultSet rs = s1.executeQuery("SELECT a FROM test")) {
try (Statement s2 = c.createStatement()) {
s2.executeUpdate("INSERT INTO test(a) VALUES (1)");
}
assert !rs.next();
}
}
}
}