Proposed fix reference that cause StackOverflowException on equals/hashCode (#501)

exclude the referredSchema from ReferenceSchema.hashCode()-equals() to avoid StackOverflowError.

Co-authored-by: tkledkov <[email protected]>

Author: tledkov

core/src/main/java/org/everit/json/schema/ReferenceSchema.java

@@ -145,7 +145,6 @@ public boolean equals(Object o) {
             return that.canEqual(this) &&
                     Objects.equals(refValue, that.refValue) &&
                     Objects.equals(unprocessedProperties, that.unprocessedProperties) &&
-                    Objects.equals(referredSchema, that.referredSchema) &&
                     Objects.equals(title, that.title) &&
                     Objects.equals(description, that.description) &&
                     super.equals(that);
@@ -156,7 +155,7 @@ public boolean equals(Object o) {
 
     @Override
     public int hashCode() {
-        return Objects.hash(super.hashCode(), referredSchema, refValue, unprocessedProperties, title, description);
+        return Objects.hash(super.hashCode(), refValue, unprocessedProperties, title, description);
     }
 
     @Override

core/src/test/java/org/everit/json/schema/ReferenceSchemaTest.java

@@ -80,7 +80,7 @@ public void definesPropertyThrowsExc_IfNoReferredSchemaIsSet() {
     public void equalsVerifier() {
         EqualsVerifier.forClass(ReferenceSchema.class)
                 .withRedefinedSuperclass()
-                .withIgnoredFields("schemaLocation", "location")
+                .withIgnoredFields("schemaLocation", "location", "referredSchema")
                 //there are specifically some non final fields for loading of recursive schemas
                 .suppress(Warning.NONFINAL_FIELDS)
                 .suppress(Warning.STRICT_INHERITANCE)

tests/vanilla/src/main/java/org/everit/json/schema/EmptyObjectTest.java

@@ -9,6 +9,8 @@
 import org.json.JSONTokener;
 import org.junit.jupiter.api.Test;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
 public class EmptyObjectTest {
 
     @Test
@@ -23,6 +25,9 @@ public void validateEmptyObject() throws IOException {
 
         Schema schema = SchemaLoader.load(jsonSchema);
         schema.validate(jsonSubject);
+
+        assertEquals(schema, SchemaLoader.load(jsonSchema));
+        assertEquals(schema.hashCode(), SchemaLoader.load(jsonSchema).hashCode());
     }
 
 }