For Eg: Street, BuildingId, FloorId, UnitId needs to be separated with ,
only when the values are not null. If any of the fields is null do not separate with a comma.
<ADDRESS nil="true"><xsl:value-of select="//street"/><xsl:text>,</xsl:text><xsl:value-of select="//buildingId"/><xsl:text>,</xsl:text><xsl:value-of select="//floorId"/><xsl:text>,</xsl:text><xsl:value-of select="//unitId"/></ADDRESS>