public void setColumns(java.util.Collection<String> columns) {
        if (columns == null) {
            this.columns = null;
            return;
        }

        this.columns = new java.util.ArrayList<String>(columns);
    }
<p>
A folder has a list of columns. A column can only be in one folder.
</p>

@param columns
       A folder has a list of columns. A column can only be in one folder.
aws-java-sdk-quicksight/src/main/java/com/amazonaws/services/quicksight/model/FieldFolder.java