xmp regression? 7.3 : Error on MetaData, Schema is not set in this document : http://ns.adobe.com/xap/1.0/sType/Dimensions#

oops, the error message has changed a little bit:
was "7.6 : Error on MetaData, Type not defined : Dimensions"

org.apache.xmpbox.xml.XmpParsingException: Schema is not set in this document : http://ns.adobe.com/xap/1.0/sType/Dimensions#
at org.apache.xmpbox.xml.DomXmpParser.checkPropertyDefinition(DomXmpParser.java:808)
at org.apache.xmpbox.xml.DomXmpParser.parseLiDescription(DomXmpParser.java:530)
at org.apache.xmpbox.xml.DomXmpParser.createProperty(DomXmpParser.java:353)
at org.apache.xmpbox.xml.DomXmpParser.parseDescriptionRoot(DomXmpParser.java:292)
at org.apache.xmpbox.xml.DomXmpParser.parse(DomXmpParser.java:206)
at org.apache.xmpbox.xml.DomXmpParser.parse(DomXmpParser.java:114)
at org.apache.pdfbox.preflight.process.MetadataValidationProcess.validate(MetadataValidationProcess.java:66)
at org.apache.pdfbox.preflight.utils.ContextHelper.callValidation(ContextHelper.java:73)
at org.apache.pdfbox.preflight.utils.ContextHelper.validateElement(ContextHelper.java:88)
at org.apache.pdfbox.preflight.PreflightDocument.validate(PreflightDocument.java:168)