Errors with Web Service model operation validation

Created WS model from simple relational model.

Validation results in the following T-editor message:

ERROR: TEIID30387 Could not load UDF "+", since its invocation class "org.teiid.query.function.FunctionMethods" could not be found.

And a ClassCastException

java.lang.ClassCastException: org.teiid82.sql.impl.xml.MappingNodeImpl cannot be cast to org.teiid.designer.xml.IMappingElement
at org.teiid.designer.transformation.aspects.sql.MappingDocumentFormatter.createMapping(MappingDocumentFormatter.java:787)
at org.teiid.designer.transformation.aspects.sql.MappingDocumentFormatter.processChildren(MappingDocumentFormatter.java:1116)
at org.teiid.designer.transformation.aspects.sql.MappingDocumentFormatter.processNamespaces(MappingDocumentFormatter.java:1196)
at org.teiid.designer.transformation.aspects.sql.MappingDocumentFormatter.createDocumentNode(MappingDocumentFormatter.java:702)
at org.teiid.designer.transformation.aspects.sql.MappingDocumentFormatter.createMapping(MappingDocumentFormatter.java:748)
at org.teiid.designer.transformation.aspects.sql.MappingDocumentFormatter.createMappingString(MappingDocumentFormatter.java:821)
at org.teiid.designer.transformation.aspects.sql.TreeMappingRootSqlAspect.getTransformation(TreeMappingRootSqlAspect.java:285)
at org.teiid.designer.transformation.aspects.sql.TreeMappingRootSqlAspect.getTransformationInfo(TreeMappingRootSqlAspect.java:333)
at org.teiid.designer.core.metadata.runtime.RuntimeAdapter.addTransformationWords(RuntimeAdapter.java:412)
at org.teiid.designer.core.metadata.runtime.RuntimeAdapter.addIndexWord(RuntimeAdapter.java:172)
at org.teiid.designer.core.index.ModelIndexer.addIndexWord(ModelIndexer.java:311)
at org.teiid.designer.core.index.ModelIndexer.index(ModelIndexer.java:164)
at org.teiid.designer.core.index.Index.add(Index.java:127)
at org.teiid.designer.core.index.ModelIndexer.indexResource(ModelIndexer.java:240)
at org.teiid.designer.core.builder.ModelBuildUtil.indexResource(ModelBuildUtil.java:308)
at org.teiid.designer.core.builder.ModelBuildUtil.indexResources(ModelBuildUtil.java:333)
at org.teiid.designer.core.builder.ModelBuildUtil.indexResources(ModelBuildUtil.java:324)
at org.teiid.designer.core.builder.ModelBuildUtil.buildResources(ModelBuildUtil.java:123)
at org.teiid.designer.core.builder.ModelBuilder$1.run(ModelBuilder.java:138)