Variable substitution fails unexpectedly with overloaded values using resolveWith()

[achohbee]

An unexpected error occurs with the following code:

// This FAILS!
Config conf = ConfigFactory.parseString("{ \"one\": \"first\", \"one\": ${variable}}")
        .resolveWith(ConfigFactory.parseString("{ \"variable\": \"second\"}"));

The expected behavior is that the value of "one" will be ${variable}, which will resolve to "second". Instead, the following exception is thrown:

com.typesafe.config.ConfigException$BugOrBroken: replace in parent not possible ConfigDelayedMerge("first",${variable}) with Quoted("first") in ResolveSource(root=SimpleConfigObject({"variable":"second"}), pathFromRoot=null)

The following code blocks work as expected, so this is definitely an edge case that involves both an overloaded value AND resolving against another config:

// This works
Config conf = ConfigFactory.parseString("{ \"one\": \"first\", \"one\": ${variable}, \"variable\": \"second\"}")
        .resolve();

// This works
Config conf = ConfigFactory.parseString("{ \"one\": ${variable}}")
        .resolveWith(ConfigFactory.parseString("{ \"variable\": \"second\"}"));

Bug is observed running with artifact com.typesafe:config:1.4.9.

[johanandren]

Do you know if this was working at some point or if it was always behaving like that?

[achohbee]

When I noticed the issue, I was running against version 1.3.2. The same error was thrown in that version. I updated to 1.4.9 to see if the issue was resolved, but the error still occurs. I haven't checked older versions.