Fix unexpected exception while getting data on WITS

[charphi]

At least one flow of WITS has a time dimension that is not the latest dimension.
This triggers a IndexOutOfBoundsException in Key.Builder.

Example: http://wits.worldbank.org/API/V1/SDMX/V21/rest/datastructure/WBG_WITS/TARIFF_TRAINS/1.1/?references=children

<DimensionList id="DimensionDescriptor" urn="urn:sdmx:org.sdmx.infomodel.datastructure.DimensionDescriptor=WBG_WITS:TARIFF_TRAINS(1.1).DimensionDescriptor">
	<Dimension id="FREQ" urn="urn:sdmx:org.sdmx.infomodel.datastructure.Dimension=WBG_WITS:TARIFF_TRAINS(1.1).FREQ" position="1">
		<ConceptIdentity>
			<Ref id="FREQ" maintainableParentID="TARIFF_CONCEPTS" maintainableParentVersion="1.0" agencyID="WBG_WITS" package="conceptscheme" class="Concept" xmlns="" />
		</ConceptIdentity>
		<LocalRepresentation>
			<Enumeration>
				<Ref id="CL_FREQ_WITS" version="1.0" agencyID="WBG_WITS" package="codelist" class="Codelist" xmlns="" />
			</Enumeration>
		</LocalRepresentation>
	</Dimension>
	<Dimension id="REPORTER" urn="urn:sdmx:org.sdmx.infomodel.datastructure.Dimension=WBG_WITS:TARIFF_TRAINS(1.1).REPORTER" position="2">
		<ConceptIdentity>
			<Ref id="REPORTER" maintainableParentID="TARIFF_CONCEPTS" maintainableParentVersion="1.0" agencyID="WBG_WITS" package="conceptscheme" class="Concept" xmlns="" />
		</ConceptIdentity>
		<LocalRepresentation>
			<Enumeration>
				<Ref id="CL_COUNTRY_WITS" version="1.0" agencyID="WBG_WITS" package="codelist" class="Codelist" xmlns="" />
			</Enumeration>
		</LocalRepresentation>
	</Dimension>
	<Dimension id="PARTNER" urn="urn:sdmx:org.sdmx.infomodel.datastructure.Dimension=WBG_WITS:TARIFF_TRAINS(1.1).PARTNER" position="3">
		<ConceptIdentity>
			<Ref id="PARTNER" maintainableParentID="TARIFF_CONCEPTS" maintainableParentVersion="1.0" agencyID="WBG_WITS" package="conceptscheme" class="Concept" xmlns="" />
		</ConceptIdentity>
		<LocalRepresentation>
			<Enumeration>
				<Ref id="CL_COUNTRY_WITS" version="1.0" agencyID="WBG_WITS" package="codelist" class="Codelist" xmlns="" />
			</Enumeration>
		</LocalRepresentation>
	</Dimension>
	<TimeDimension id="TIME_PERIOD" urn="urn:sdmx:org.sdmx.infomodel.datastructure.TimeDimension=WBG_WITS:TARIFF_TRAINS(1.1).TIME_PERIOD" position="4">
		<ConceptIdentity>
			<Ref id="YEAR" maintainableParentID="TARIFF_CONCEPTS" maintainableParentVersion="1.0" agencyID="WBG_WITS" package="conceptscheme" class="Concept" xmlns="" />
		</ConceptIdentity>
		<LocalRepresentation>
			<TextFormat textType="ObservationalTimePeriod" />
		</LocalRepresentation>
	</TimeDimension>
	<Dimension id="PRODUCTCODE" urn="urn:sdmx:org.sdmx.infomodel.datastructure.Dimension=WBG_WITS:TARIFF_TRAINS(1.1).PRODUCTCODE" position="5">
		<ConceptIdentity>
			<Ref id="PRODUCTCODE" maintainableParentID="TARIFF_CONCEPTS" maintainableParentVersion="1.0" agencyID="WBG_WITS" package="conceptscheme" class="Concept" xmlns="" />
		</ConceptIdentity>
		<LocalRepresentation>
			<Enumeration>
				<Ref id="CL_PRODUCTCODE_WITS" version="1.0" agencyID="WBG_WITS" package="codelist" class="Codelist" xmlns="" />
			</Enumeration>
		</LocalRepresentation>
	</Dimension>
	<Dimension id="DATATYPE" urn="urn:sdmx:org.sdmx.infomodel.datastructure.Dimension=WBG_WITS:TARIFF_TRAINS(1.1).DATATYPE" position="6">
		<ConceptIdentity>
			<Ref id="DATATYPE" maintainableParentID="TARIFF_CONCEPTS" maintainableParentVersion="1.0" agencyID="WBG_WITS" package="conceptscheme" class="Concept" xmlns="" />
		</ConceptIdentity>
		<LocalRepresentation>
			<Enumeration>
				<Ref id="CL_DATATYPE_WITS" version="1.0" agencyID="WBG_WITS" package="codelist" class="Codelist" xmlns="" />
			</Enumeration>
		</LocalRepresentation>
	</Dimension>
</DimensionList>

Same example with cli:

> sdmx-dl list concepts WITS DF_WITS_Tariff_TRAINS --sort | convertfrom-csv | format-table

Concept           Label             Type      Coded Position
-------           -----             ----      ----- --------
FREQ              Freq              dimension true  1
REPORTER          Reporter_ISO_N    dimension true  2
PARTNER           Partner           dimension true  3
PRODUCTCODE       ProductCode       dimension true  5
DATATYPE          DataType          dimension true  6
DATASOURCE        DataSource        attribute true
EXCLUDEDFROM      ExcludedFrom      attribute true

[charphi]

Done in b4631dd