JsonEncoder produces invalid json when suppressing throwable

[bhurwitz-yottaa]

Using some combinations of the configurations for the JsonEncoder that do not include all the available properties, the log entries will generate invalid json (dangling comma before closing brace).

Example that fails:

        <encoder class="ch.qos.logback.classic.encoder.JsonEncoder">
            <withLoggerName>true</withLoggerName>
            <withFormattedMessage>true</withFormattedMessage>
            <withMessage>false</withMessage>
            <withSequenceNumber>false</withSequenceNumber>
            <withContext>false</withContext>
            <withNanoseconds>false</withNanoseconds>
            <withMDC>false</withMDC>
            <withArguments>false</withArguments>
            <withTimestamp>true</withTimestamp>
            <withThrowable>false</withThrowable>
        </encoder>

You can work around this by not including <withThrowable>false</withThrowable> but this forces the user to log unwanted characters.

There are multiple spots in the code for inclusion of the properties that naively append a "," after their inclusion, this is part of the problem.

[ceki]

@bhurwitz-yottaa Fixed in commit cbbd820