clean up confusing message in slice processing

org.hl7.fhir.utilities/src/main/resources/Messages.properties

@@ -273,8 +273,8 @@ FHIRPATH_DECIMAL_ONLY = Error evaluating FHIRPath expression: The function {0} c
 FHIRPATH_DISCRIMINATOR_BAD_NAME = Invalid function name {0}() in discriminator
 FHIRPATH_DISCRIMINATOR_BAD_SYNTAX_CONST = Invalid expression syntax in discriminator (const)
 FHIRPATH_DISCRIMINATOR_BAD_SYNTAX_GROUP = Invalid expression syntax in discriminator (group ''{0}'')
-FHIRPATH_DISCRIMINATOR_CANT_FIND = Unable to resolve discriminator in definitions: {0} in profile {1} on element {2}, looking in profile {3}
-FHIRPATH_DISCRIMINATOR_CANT_FIND_EXTENSION = Unable to resolve discriminator {0} on {2} found in the definitions because the extension {1} wasn''t found in the profile {3}
+FHIRPATH_DISCRIMINATOR_CANT_FIND = Unable to resolve discriminator in definitions: ''{0}'' in profile ''{1}'' on element ''{2}'', looking in profile ''{3}''
+FHIRPATH_DISCRIMINATOR_CANT_FIND_EXTENSION = Unable to resolve discriminator ''{0}'' on ''{2}'' found in the definitions because the extension ''{1}'' wasn''t found in the profile ''{3}''
 FHIRPATH_DISCRIMINATOR_MULTIPLE_PROFILES_one =
 FHIRPATH_DISCRIMINATOR_MULTIPLE_PROFILES_other = Error in discriminator at {1}: no children, {0} type profiles
 FHIRPATH_DISCRIMINATOR_MULTIPLE_TYPES_one =