src/main/java/com/cedarsoftware/util/io/JsonWriter.java
private void writeCollectionElement(Object o) throws IOException
    {
        if (o == null)
        {
            out.write("null");
        }
        else if (o instanceof Boolean || o instanceof Double)
        {
            writePrimitive(o, false);
        }
        else if (o instanceof Long)
        {
            writePrimitive(o, writeLongsAsStrings);
        }
        else if (o instanceof String)
        {   // Never do an @ref to a String (they are treated as logical primitives and intern'ed on read)
            writeJsonUtf8String((String) o, out);
        }
        else if (neverShowType && MetaUtils.isPrimitive(o.getClass()))
        {   // If neverShowType, then force primitives (and primitive wrappers)
            // to be output with toString() - prevents {"value":6} for example
            writePrimitive(o, false);
        }
        else
        {
            writeImpl(o, true);
        }
    }
private void writeCollectionElement(Object o) throws IOException
    {
        if (o == null)
        {
            out.write("null");
        }
        else if (o instanceof Boolean || o instanceof Double)
        {
            writePrimitive(o, false);
        }
        else if (o instanceof Long)
        {
            writePrimitive(o, writeLongsAsStrings);
        }
        else if (o instanceof String)
        {   // Never do an @ref to a String (they are treated as logical primitives and intern'ed on read)
            writeJsonUtf8String((String) o, out);
        }
        else if (neverShowType && MetaUtils.isPrimitive(o.getClass()))
        {   // If neverShowType, then force primitives (and primitive wrappers)
            // to be output with toString() - prevents {"value":6} for example
            writePrimitive(o, false);
        }
        else
        {
            writeImpl(o, true);
        }
    }
Write an element that is contained in some type of Collection or Map.
@param o Collection element to output in JSON format.
@throws IOException if an error occurs writing to the output stream.