String TO Missing Value

I am looking to transform a string with a placeholder value into a "missing value", but am not seeing that option in any of the Knime nodes.

Really, I'm looking to combine two columns with the "Column Merger" node, which is perfect for my purposes... except that I have this placeholder value, rather than a Java missing value.  

I'm trying to avoid a really ugly workaround of splitting the file into those with placeholder values and those without, then ditching the column of only-placeholder values, renaming the other column, filtering, then concatenating, and then proceeding.  

Many thanks in advance!

Use the Rule Engine node for your task. Because, if no rule matches, the output of this node will be a missing value. ;-)

Or a java snippet, something like:

String newValue = oldValue.equals("placeholder_for_missing") ? null : oldValue;

where newValue is then returned as your string column, and oldValue is the incoming value