Drop federation key authorities in export metadata. Drop all but expl…

…icitly opted-in entities in export metadata.

build/uk_master_export.xsl

@@ -43,6 +43,28 @@
 		</xsl:comment>
 		<xsl:apply-templates/>
 	</xsl:template>
+
+	<!--
+		Drop the federation-specific key authority information.
+		
+		We assume, for now, that this is the only extension on the EntitiesDescriptor
+		and just omit that entirely.  If we ever start putting other extensions in at
+		that level, this would need to be revised.
+	-->
+	<xsl:template match="md:EntitiesDescriptor/md:Extensions">
+		<!-- do nothing -->
+	</xsl:template>
+
+	<!--
+		Only include explicitly opted-in entities by discarding
+		everything else.
+		
+		There must be at least one of these, or the output will
+		not be schema-valid.
+	-->
+	<xsl:template match="md:EntityDescriptor[not(md:Extensions/uklabel:ExportOptIn)]">
+		<!-- do nothing -->
+	</xsl:template>
 
 	<!--
 		Pass through certain uklabel namespace elements.