Handling of cross-service references

[HeikoTheissen]

Proposal: Expose external entities as abstract objects:

odata-openapi/tools/tests/ref-error.openapi3.json

Lines 3488 to 3491 in 34c1763

	"com.sap.gateway.default.loandisbursementrequest.v0001.BasicDataLoanDisbursementRequest": {
	"description": "External entity",
	"type": "object"
	},

To generate these additional /components/schemas, the XSL transformations needs to select external type references, which is not straightforward with the current code. With the approach of #291, this can be done as

odata-openapi/tools/V4-CSDL-to-OpenAPI.xsl

Lines 587 to 594 in 9d87d8e

	<xsl:apply-templates
	select="/edmx:Edmx/edmx:DataServices/edm:Schema/edm:EntityType
	|/edmx:Edmx/edmx:DataServices/edm:Schema/edm:ComplexType
	|/edmx:Edmx/edmx:DataServices/edm:Schema/edm:TypeDefinition
	|/edmx:Edmx/edmx:DataServices/edm:Schema/edm:EnumType
	|/edmx:Edmx/edmx:DataServices/edm:Schema/edm:EntityContainer
	|//edm:NavigationProperty[not(@p1:Type)]"
	mode="hash">

odata-openapi/tools/V4-CSDL-to-OpenAPI.xsl

Lines 1459 to 1463 in 9d87d8e

	<xsl:template match="edm:NavigationProperty" mode="hashpair">
	<xsl:text>"</xsl:text>
	<xsl:value-of select="@p2:Type" />
	<xsl:text>":{"description":"External entity","type":"object"}</xsl:text>
	</xsl:template>