!fixup Add support for validation of length facet

- add support for length, also set minLength and maxLength with the value of length, when hasLength is true, and those variables are queried
- ensure length and minLength and maxLength facets are not declared together (Xerces Error, but we have asserts incase Xerces validation is turned off)
- fix error message for isSimpleType check in computeMinMaxLength and length definitions
- add tests for validation=limited and validation=on
- added hexBinary tests including test with length=0

DAFFODIL-2842

daffodil-core/src/main/scala/org/apache/daffodil/core/dsom/ElementBase.scala

@@ -966,7 +966,7 @@ trait ElementBase
     Assert.invariant(hasLength)
     schemaDefinitionUnless(
       isSimpleType,
-      "Facet length is allowed only on types string and hexBinary.",
+      "Facet length is allowed only on simple types or types derived from simple types.",
     )
     typeDef match {
       case _ if hasRepType => {
@@ -1037,7 +1037,7 @@ trait ElementBase
   private def computeMinMaxLength: (java.math.BigDecimal, java.math.BigDecimal) = {
     schemaDefinitionUnless(
       isSimpleType,
-      "Facets minLength and maxLength are allowed only on types string and hexBinary.",
+      "Facets minLength and maxLength are allowed only on simple types or types derived from simple types.",
     )
     typeDef match {
       case _ if hasRepType => {

daffodil-test/src/test/resources/org/apache/daffodil/section02/validation_errors/Validation.tdml

@@ -442,6 +442,14 @@
         </xs:simpleType>
     </xs:element>
 
+    <xs:element name="e2_8" dfdl:lengthKind="delimited" dfdl:encoding="iso-8859-1">
+        <xs:simpleType>
+            <xs:restriction base="xs:hexBinary">
+                <xs:length value="0"/>
+            </xs:restriction>
+        </xs:simpleType>
+    </xs:element>
+
       <xs:element name="e3_2" dfdl:lengthKind="delimited">
       <xs:simpleType>
         <xs:restriction base="ex:stMaxLength_2">
@@ -710,6 +718,30 @@
             </tdml:dfdlInfoset>
         </tdml:infoset>
     </tdml:parserTestCase>
+
+    <tdml:parserTestCase name="validation_testFacets_03"
+                         root="e2_8" model="TestFacets"
+                         description="checks that int doesn't work with length facet"
+                         validation="limited">
+
+        <tdml:document>
+            <tdml:documentPart type="byte">deadbeefdafada</tdml:documentPart>
+        </tdml:document>
+
+        <tdml:infoset>
+            <tdml:dfdlInfoset>
+                <ex:e2_8>DEADBEEFDAFADA</ex:e2_8>
+            </tdml:dfdlInfoset>
+        </tdml:infoset>
+
+        <tdml:validationErrors>
+
+            <tdml:error>e2_8</tdml:error>
+            <tdml:error>failed facet checks</tdml:error>
+            <tdml:error>facet length (0)</tdml:error>
+
+        </tdml:validationErrors>
+    </tdml:parserTestCase>
 <!--
     Test name: checkEnumeration_Pass_limited
        Schema: TestFacets

daffodil-test/src/test/scala/org/apache/daffodil/section02/validation_errors/TestValidationErr.scala

@@ -187,6 +187,9 @@ class TestValidationErr {
   @Test def test_validation_testFacets_02(): Unit = {
     runner.runOneTest("validation_testFacets_02")
   }
+  @Test def test_validation_testFacets_03(): Unit = {
+    runner.runOneTest("validation_testFacets_03")
+  }
   @Test def test_validation_testFacets2_01(): Unit = {
     runner.runOneTest("validation_testFacets2_01")
   }