Bug in JDBC.driver CopyManager method when copying json output

Dear JDBC-Devs,
i think i found an escaping bug that causes duplicate escaping with backslash when using jdbc drivers CopyManager with JSON results.

Sample Query:
select to_json( 'my name is "rabbit"'::text);

Executing this query as Statement
<java>
Statement statement = connection.createStatement()
ResultSet resultSet = statement.executeQuery("select to_json('my name is \"rabbit\"'::text)");
String result=resultSet.next().getString(1);// => "my name is \"rabbit\""
</java>

Execution of this query using CopyManager (see result file attachment)
This Execution does the duplicate escaping for JSON output causing invalid json text.
<java>
BaseConnection bc=(BaseConnection) connection;
final CopyManager cm=new CopyManager(bc);
File someFile=new File("test.json");
try(FileWriter fw=new FileWriter(someFile)){
cm.copyOut("COPY (select to_json('my name is \"rabbit\"'::text)) TO STDOUT WITH NULL AS ''", fw);
// => my name is \\"rabbit\\" instead
}
</java>

My Driver:
<dependency>
<groupId>org.postgresql</groupId>
<artifactId>postgresql</artifactId>
<version>42.2.5</version>
</dependency>

My pg Server (Docker):
10.4 (Debian 10.4-2.pgdg90+1)

If that is required behavior I suggest to introduce another format "json" in addition to "text" and "csv".

Kind regards

Gerson Stadlmann
Manager Software Development International

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