feat: allow duplication in schema element names (#338)

This commit relaxes validation DUPL-011, which, until now,
strictly forbade schema element name duplications.

This PR changes so that element names are allowed to be duplicates
if they are equivalent. E.g. they share both the schema type
and graph pattern.

Co-authored-by: Florent Biville <florent.biville@neo4j.com>

Author: nord-erik

core/src/main/java/org/neo4j/importer/v1/targets/EntityTarget.java

@@ -69,6 +69,8 @@ public <T extends EntityTargetExtension> Optional<T> getExtension(Class<T> type)
                 .findFirst();
     }
 
+    public abstract Schema getSchema();
+
     @Override
     public boolean equals(Object o) {
         if (!(o instanceof EntityTarget)) return false;

core/src/main/java/org/neo4j/importer/v1/targets/NodeTarget.java

@@ -24,9 +24,7 @@
 import java.util.Objects;
 
 public class NodeTarget extends EntityTarget {
-
     private final List<String> labels;
-
     private final NodeSchema schema;
 
     @JsonCreator

core/src/main/java/org/neo4j/importer/v1/validation/plugin/NoDuplicatedSchemaNameValidator.java

@@ -24,7 +24,7 @@
 
 public class NoDuplicatedSchemaNameValidator implements SpecificationValidator {
     private static final String ERROR_CODE = "DUPL-011";
-    private final List<SchemaElement> elements = new ArrayList<>();
+    private final Set<SchemaElement> elements = new LinkedHashSet<>();
 
     @Override
     public Set<Class<? extends SpecificationValidator>> requires() {
@@ -53,7 +53,7 @@ public void visitRelationshipTarget(int index, RelationshipTarget target) {
     public boolean report(Builder builder) {
         var duplicates = elements.stream().collect(Collectors.groupingBy(SchemaElement::getName)).entrySet().stream()
                 .filter(e -> e.getValue().size() > 1)
-                .collect(Collectors.toList());
+                .collect(Collectors.toCollection(LinkedHashSet::new));
 
         duplicates.forEach(dup -> builder.addError(
                 dup.getValue().get(0).getPath(),
@@ -115,6 +115,19 @@ public String getName() {
         public String getPath() {
             return path;
         }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            ConstraintElement that = (ConstraintElement) o;
+            return Objects.equals(constraint, that.constraint);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(constraint);
+        }
     }
 
     private static class IndexElement implements SchemaElement {
@@ -133,5 +146,18 @@ public String getName() {
         public String getPath() {
             return path;
         }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            IndexElement that = (IndexElement) o;
+            return Objects.equals(index, that.index);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(index);
+        }
     }
 }