Apache Velocity - if clause

I use Apache Velocity for create an e-mail template. I have a mail message that contain a table with a list of elements, for create it I had used a #foreach.

In this table I'll add a column contained a conditional string, If the element is empty the string are string1 if is not empty are string2.

This is my code:

    <td style="max-width: 140px; word-wrap: break-word;">
#if(${value} not null) 'String1' #else 'String2'#end</td>

I don't find any help in stack... anyone can help me?