Invalid character in the generated XML object

[Izochrone]

I got an error that I haven't seen yet before.

On the service side, I have a .Net ODATA service (.Net 4.0), and there is an error on saving the incoming objects:

An error occured: System.Data.Services.DataServiceException
An error occurred while processing this request.
Stacktrace:    at: System.Data.Services.Serializers.ODataMessageReaderDeserializer.Deserialize(SegmentInfo segmentInfo)
   at: System.Data.Services.Serializers.Deserializer.ReadEntity(ResourceType& entityTypeInPayload)
   at: System.Data.Services.Serializers.Deserializer.HandlePutRequest()
   at: System.Data.Services.DataService`1.HandlePutOperation(RequestDescription description, IDataService dataService)
   at: System.Data.Services.DataService`1.ProcessIncomingRequest(RequestDescription description, IDataService dataService)
   at: System.Data.Services.DataService`1.HandleNonBatchRequest(RequestDescription description)
   at: System.Data.Services.DataService`1.HandleRequest()

Inner exception: The „ US” (hexadecimal value: 0x1F) is an invalid character. Row: 1, position: 753.
Stacktrace:    at: System.Xml.XmlTextReaderImpl.Throw(String res, String[] args)
   at: System.Xml.XmlTextReaderImpl.ParseText(Int32& startPos, Int32& endPos, Int32& outOrChars)
   at: System.Xml.XmlTextReaderImpl.ParseText()
   at: System.Xml.XmlTextReaderImpl.ParseElementContent()
   at: Microsoft.Data.OData.Atom.BufferingXmlReader.ReadInternal(Boolean ignoreInStreamErrors)
   at: Microsoft.Data.OData.Atom.BufferingXmlReader.ReadNextAndCheckForInStreamError()
   at: Microsoft.Data.OData.Atom.BufferingXmlReader.ReadInternal(Boolean ignoreInStreamErrors)
   at: Microsoft.Data.OData.Atom.BufferingXmlReader.Read()
   at: Microsoft.Data.OData.Atom.XmlReaderExtensions.ReadElementContentValue(XmlReader reader)
   at: Microsoft.Data.OData.AtomValueUtils.ReadPrimitiveValue(XmlReader reader, IEdmPrimitiveTypeReference primitiveTypeReference)
   at: Microsoft.Data.OData.Atom.ODataAtomPropertyAndValueDeserializer.ReadNonEntityValueImplementation(IEdmTypeReference expectedTypeReference, DuplicatePropertyNamesChecker duplicatePropertyNamesChecker, CollectionWithoutExpectedTypeValidator collectionValidator, Boolean validateNullValue, Boolean epmPresent, String propertyName)
   at: Microsoft.Data.OData.Atom.ODataAtomPropertyAndValueDeserializer.ReadProperty(String expectedPropertyName, IEdmTypeReference expectedPropertyTypeReference, ODataNullValueBehaviorKind nullValueReadBehaviorKind, Boolean epmPresent)
   at: Microsoft.Data.OData.Atom.ODataAtomPropertyAndValueDeserializer.ReadPropertiesImplementation(IEdmStructuredType structuredType, ReadOnlyEnumerable`1 properties, DuplicatePropertyNamesChecker duplicatePropertyNamesChecker, Boolean epmPresent)
   at: Microsoft.Data.OData.Atom.ODataAtomEntryAndFeedDeserializer.ReadAtomContentElement(IODataAtomReaderEntryState entryState)
   at: Microsoft.Data.OData.Atom.ODataAtomEntryAndFeedDeserializer.ReadAtomElementInEntry(IODataAtomReaderEntryState entryState)
   at: Microsoft.Data.OData.Atom.ODataAtomEntryAndFeedDeserializer.ReadEntryContent(IODataAtomReaderEntryState entryState)
   at: Microsoft.Data.OData.Atom.ODataAtomReader.ReadAtEntryStartImplementation()
   at: Microsoft.Data.OData.ODataReaderCore.ReadImplementation()
   at: Microsoft.Data.OData.ODataReaderCore.InterceptException[T](Func`1 action)
   at: System.Data.Services.Serializers.EntityDeserializer.ReadEntry(ODataReader odataReader, SegmentInfo topLevelSegmentInfo)
   at: System.Data.Services.Serializers.EntityDeserializer.Read(SegmentInfo segmentInfo)
   at: System.Data.Services.Serializers.ODataMessageReaderDeserializer.Deserialize(SegmentInfo segmentInfo)

   at: System.Data.Services.Serializers.ODataMessageReaderDeserializer.Deserialize(SegmentInfo segmentInfo)
   at: System.Data.Services.Serializers.Deserializer.ReadEntity(ResourceType& entityTypeInPayload)
   at: System.Data.Services.Serializers.Deserializer.HandlePutRequest()
   at: System.Data.Services.DataService`1.HandlePutOperation(RequestDescription description, IDataService dataService)
   at: System.Data.Services.DataService`1.ProcessIncomingRequest(RequestDescription description, IDataService dataService)
   at: System.Data.Services.DataService`1.HandleNonBatchRequest(RequestDescription description)
   at: System.Data.Services.DataService`1.HandleRequest()

Where could the UNIT SEPARATOR character be generated in the code of odata4j? Can you give me some hint of where to fix this in the source?