Check for empty xs:string elements in MDUI. The standard also forbids…

… xs:string elements which contain only whitespace, but that is a very hard to do in XSLT so these checks should be redone in Java at some point.

build/check_mdui.xsl

@@ -27,6 +27,42 @@
 	-->
 	<xsl:import href="check_framework.xsl"/>
 
+	<!--
+		General SAML constraint that xs:string elements must contain at least one
+		non-whitespace character.  That's actually too hard to do in XSLT so we'll
+		restrict ourselves to a check for empty elements for now.
+	-->
+	<xsl:template match="mdui:DisplayName[. = '']">
+		<xsl:call-template name="error">
+			<xsl:with-param name="m">mdui:DisplayName must not be empty</xsl:with-param>
+		</xsl:call-template>        
+	</xsl:template>
+	<xsl:template match="mdui:Description[. = '']">
+		<xsl:call-template name="error">
+			<xsl:with-param name="m">mdui:Description must not be empty</xsl:with-param>
+		</xsl:call-template>        
+	</xsl:template>
+	<xsl:template match="mdui:Keywords[. = '']">
+		<xsl:call-template name="error">
+			<xsl:with-param name="m">mdui:Keywords must not be empty</xsl:with-param>
+		</xsl:call-template>        
+	</xsl:template>
+	<xsl:template match="mdui:IPHint[. = '']">
+		<xsl:call-template name="error">
+			<xsl:with-param name="m">mdui:IPHint must not be empty</xsl:with-param>
+		</xsl:call-template>        
+	</xsl:template>
+	<xsl:template match="mdui:DomainHint[. = '']">
+		<xsl:call-template name="error">
+			<xsl:with-param name="m">mdui:DomainHint must not be empty</xsl:with-param>
+		</xsl:call-template>        
+	</xsl:template>
+	<xsl:template match="mdui:GeolocationHint[. = '']">
+		<xsl:call-template name="error">
+			<xsl:with-param name="m">mdui:GeolocationHint must not be empty</xsl:with-param>
+		</xsl:call-template>        
+	</xsl:template>
+
 	<!--
 		Section 2.1