use linked hash maps where it matters

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

@@ -1,23 +1,24 @@
 package org.everit.json.schema;
 
-import static java.util.Objects.requireNonNull;
-import static java.util.stream.Collectors.toMap;
-import static org.everit.json.schema.JSONPointer.unescape;
+import org.everit.json.schema.regexp.JavaUtilRegexpFactory;
+import org.everit.json.schema.regexp.Regexp;
+import org.everit.json.schema.regexp.RegexpFactory;
 
 import java.util.AbstractMap;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
 import java.util.regex.Pattern;
 
-import org.everit.json.schema.regexp.JavaUtilRegexpFactory;
-import org.everit.json.schema.regexp.Regexp;
-import org.everit.json.schema.regexp.RegexpFactory;
+import static java.util.Objects.requireNonNull;
+import static java.util.stream.Collectors.toMap;
+import static org.everit.json.schema.JSONPointer.unescape;
 
 /**
  * Object schema validator.
@@ -35,11 +36,11 @@ private static final Regexp toRegexp(String pattern) {
             return DEFAULT_REGEXP_FACTORY.createHandler(pattern);
         }
 
-        private final Map<Regexp, Schema> patternProperties = new HashMap<>();
+        private final Map<Regexp, Schema> patternProperties = new LinkedHashMap<>();
 
         private boolean requiresObject = true;
 
-        private final Map<String, Schema> propertySchemas = new HashMap<>();
+        private final Map<String, Schema> propertySchemas = new LinkedHashMap<>();
 
         private boolean additionalProperties = true;
 
@@ -51,9 +52,9 @@ private static final Regexp toRegexp(String pattern) {
 
         private Integer maxProperties;
 
-        private final Map<String, Set<String>> propertyDependencies = new HashMap<>();
+        private final Map<String, Set<String>> propertyDependencies = new LinkedHashMap<>();
 
-        private final Map<String, Schema> schemaDependencies = new HashMap<>();
+        private final Map<String, Schema> schemaDependencies = new LinkedHashMap<>();
 
         private Schema propertyNameSchema;
 
@@ -167,7 +168,7 @@ public static Builder builder() {
     }
 
     private static <K, V> Map<K, V> copyMap(Map<K, V> original) {
-        return Collections.unmodifiableMap(new HashMap<>(original));
+        return Collections.unmodifiableMap(new LinkedHashMap<>(original));
     }
 
     private final Map<String, Schema> propertySchemas;

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

@@ -1,11 +1,11 @@
 package org.everit.json.schema;
 
-import static java.util.Objects.requireNonNull;
-
-import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Objects;
 
+import static java.util.Objects.requireNonNull;
+
 /**
  * This class is used by {@link org.everit.json.schema.loader.SchemaLoader} to resolve JSON pointers
  * during the construction of the schema. This class has been made mutable to permit the loading of
@@ -44,7 +44,7 @@ public Builder refValue(String refValue) {
 
         @Override public ReferenceSchema.Builder unprocessedProperties(Map<String, Object> unprocessedProperties) {
             if (retval != null) {
-                retval.unprocessedProperties = new HashMap<>(unprocessedProperties);
+                retval.unprocessedProperties = new LinkedHashMap<>(unprocessedProperties);
             }
             super.unprocessedProperties(unprocessedProperties);
             return this;

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

@@ -1,14 +1,15 @@
 package org.everit.json.schema;
 
-import static java.util.Collections.unmodifiableMap;
+import org.everit.json.schema.internal.JSONPrinter;
+import org.json.JSONWriter;
 
 import java.io.StringWriter;
 import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Objects;
 
-import org.everit.json.schema.internal.JSONPrinter;
-import org.json.JSONWriter;
+import static java.util.Collections.unmodifiableMap;
 
 /**
  * Superclass of all other schema validator classes of this package.
@@ -41,7 +42,7 @@ public abstract static class Builder<S extends Schema> {
 
         private Boolean writeOnly = null;
 
-        public Map<String, Object> unprocessedProperties = new HashMap<>(0);
+        public Map<String, Object> unprocessedProperties = new LinkedHashMap<>(0);
 
         public Builder<S> title(String title) {
             this.title = title;
@@ -137,7 +138,7 @@ protected Schema(Builder<?> builder) {
         this.nullable = builder.nullable;
         this.readOnly = builder.readOnly;
         this.writeOnly = builder.writeOnly;
-        this.unprocessedProperties = new HashMap<>(builder.unprocessedProperties);
+        this.unprocessedProperties = new LinkedHashMap<>(builder.unprocessedProperties);
     }
 
     /**

core/src/main/java/org/everit/json/schema/loader/JsonObject.java

@@ -1,17 +1,17 @@
 package org.everit.json.schema.loader;
 
-import static java.lang.String.format;
-import static java.util.Collections.unmodifiableMap;
-import static java.util.Collections.unmodifiableSet;
+import org.everit.json.schema.SchemaException;
 
-import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
 import java.util.function.Consumer;
 import java.util.function.Function;
 
-import org.everit.json.schema.SchemaException;
+import static java.lang.String.format;
+import static java.util.Collections.unmodifiableMap;
+import static java.util.Collections.unmodifiableSet;
 
 /**
  * @author erosb
@@ -97,7 +97,7 @@ private void iterateOnEntry(Map.Entry<String, Object> entry, JsonObjectIterator
     }
 
     @Override protected Object unwrap() {
-        return new HashMap<>(storage);
+        return new LinkedHashMap<>(storage);
     }
 
     Map<String, Object> toMap() {

core/src/main/java/org/everit/json/schema/loader/JsonValue.java

@@ -1,21 +1,21 @@
 package org.everit.json.schema.loader;
 
-import static org.everit.json.schema.loader.OrgJsonUtil.toList;
-import static org.everit.json.schema.loader.OrgJsonUtil.toMap;
-import static org.everit.json.schema.loader.SpecificationVersion.DRAFT_4;
+import org.everit.json.schema.SchemaException;
+import org.json.JSONArray;
+import org.json.JSONObject;
 
-import java.util.HashMap;
 import java.util.HashSet;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
 import java.util.function.Consumer;
 import java.util.function.Function;
 
-import org.everit.json.schema.SchemaException;
-import org.json.JSONArray;
-import org.json.JSONObject;
+import static org.everit.json.schema.loader.OrgJsonUtil.toList;
+import static org.everit.json.schema.loader.OrgJsonUtil.toMap;
+import static org.everit.json.schema.loader.SpecificationVersion.DRAFT_4;
 
 /**
  * @author erosb
@@ -24,7 +24,7 @@ class JsonValue {
 
     class Multiplexer<R> {
 
-        protected Map<Class<?>, Function<?, R>> actions = new HashMap<>();
+        protected Map<Class<?>, Function<?, R>> actions = new LinkedHashMap<>();
 
         Multiplexer(Class<?> expectedType, Function<?, R> mapper) {
             actions.put(expectedType, mapper);

core/src/main/java/org/everit/json/schema/loader/OrgJsonUtil.java

@@ -3,6 +3,7 @@
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Iterator;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 
@@ -19,7 +20,7 @@ public class OrgJsonUtil {
      * Used as a replacement of {@code JSONObject#toMap()} (which doesn't exist in the android version of org.json).
      */
     public static Map<String, Object> toMap(JSONObject obj) {
-        Map<String, Object> rval = new HashMap<>(obj.length());
+        Map<String, Object> rval = new LinkedHashMap<>(obj.length());
         Iterator<String> keyIt = obj.keys();
         while (keyIt.hasNext()) {
             String key = keyIt.next();

core/src/main/java/org/everit/json/schema/loader/ProjectedJsonObject.java

@@ -1,17 +1,17 @@
 package org.everit.json.schema.loader;
 
-import static java.lang.String.format;
-import static java.util.Collections.emptyMap;
-import static java.util.Objects.requireNonNull;
-
-import java.util.HashMap;
 import java.util.HashSet;
+import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
 import java.util.function.Consumer;
 import java.util.function.Function;
 
+import static java.lang.String.format;
+import static java.util.Collections.emptyMap;
+import static java.util.Objects.requireNonNull;
+
 class ProjectedJsonObject extends JsonObject {
 
     private final JsonObject original;
@@ -89,13 +89,13 @@ private void throwExceptionIfNotVisible(String key) {
     }
 
     @Override protected Object unwrap() {
-        Map<String, Object> storage = new HashMap<>(original.storage);
+        Map<String, Object> storage = new LinkedHashMap<>(original.storage);
         removeHiddenKeysFrom(storage);
         return storage;
     }
 
     @Override Map<String, Object> toMap() {
-        Map<String, Object> map = new HashMap<>(original.toMap());
+        Map<String, Object> map = new LinkedHashMap<>(original.toMap());
         removeHiddenKeysFrom(map);
         return map;
     }

core/src/main/java/org/everit/json/schema/loader/ReferenceLookup.java

@@ -7,6 +7,7 @@
 import java.net.URISyntaxException;
 import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 
@@ -61,9 +62,9 @@ static Map<String, Object> extend(Map<String, Object> additional, Map<String, Ob
         if (original.keySet().isEmpty()) {
             return additional;
         }
-        Map<String, Object> rawObj = new HashMap<>();
-        original.forEach(rawObj::put);
-        additional.forEach(rawObj::put);
+        Map<String, Object> rawObj = new LinkedHashMap<>();
+        rawObj.putAll(original);
+        rawObj.putAll(additional);
         return rawObj;
     }
 
@@ -111,7 +112,7 @@ private Map<String, Object> doExtend(Map<String, Object> additional, Map<String,
     }
 
     Map<String, Object> withoutRef(JsonObject original) {
-        Map<String, Object> rawObj = new HashMap<>();
+        Map<String, Object> rawObj = new LinkedHashMap<>();
         original.keySet().stream()
                 .filter(name -> !"$ref".equals(name))
                 .forEach(name -> rawObj.put(name, original.get(name)));

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

@@ -1,10 +1,10 @@
 package org.everit.json.schema;
 
-import java.util.HashMap;
-import java.util.Map;
-
 import org.json.JSONObject;
 
+import java.util.LinkedHashMap;
+import java.util.Map;
+
 public class DynamicReferenceSchemaExample {
 
     public static void main(String[] args) {
@@ -14,7 +14,7 @@ public static void main(String[] args) {
             .build();
         rootSchema.addPropertySchema("myProperty", referenceSchema);
 
-        Map<String, Object> unprocessed = new HashMap<>();
+        Map<String, Object> unprocessed = new LinkedHashMap<>();
         JSONObject defs = new JSONObject();
         StringSchema referredSchema = StringSchema.builder()
             .minLength(2).maxLength(5)

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

@@ -15,29 +15,29 @@
  */
 package org.everit.json.schema;
 
-import static java.util.Arrays.asList;
-import static java.util.stream.Collectors.toMap;
-import static org.everit.json.schema.JSONMatcher.sameJsonAs;
-import static org.everit.json.schema.TestSupport.buildWithLocation;
-import static org.everit.json.schema.TestSupport.loadAsV6;
-import static org.hamcrest.MatcherAssert.assertThat;
-import static org.junit.jupiter.api.Assertions.*;
-
-import java.util.AbstractMap;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.concurrent.Callable;
-
+import com.google.re2j.Pattern;
+import nl.jqno.equalsverifier.EqualsVerifier;
+import nl.jqno.equalsverifier.Warning;
 import org.everit.json.schema.loader.SchemaLoader;
 import org.json.JSONObject;
 import org.json.JSONPointer;
 import org.junit.jupiter.api.Test;
 
-import com.google.re2j.Pattern;
+import java.util.AbstractMap;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.Callable;
 
-import nl.jqno.equalsverifier.EqualsVerifier;
-import nl.jqno.equalsverifier.Warning;
+import static java.util.Arrays.asList;
+import static java.util.stream.Collectors.toMap;
+import static org.everit.json.schema.JSONMatcher.sameJsonAs;
+import static org.everit.json.schema.TestSupport.buildWithLocation;
+import static org.everit.json.schema.TestSupport.loadAsV6;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.fail;
 
 public class ObjectSchemaTest {
 
@@ -259,7 +259,7 @@ public void patternPropertyTranslation() {
         ObjectSchema subject = ObjectSchema.builder()
                 .patternProperty(java.util.regex.Pattern.compile("b_.*"), BooleanSchema.INSTANCE)
                 .build();
-        Map<java.util.regex.Pattern, Schema> expected = new HashMap<>();
+        Map<java.util.regex.Pattern, Schema> expected = new LinkedHashMap<>();
         expected.put(java.util.regex.Pattern.compile("b_.*"), BooleanSchema.INSTANCE);
         assertEquals(toStringToSchemaMap(expected), toStringToSchemaMap(subject.getPatternProperties()));
     }

core/src/test/java/org/everit/json/schema/internal/JSONPrinterTest.java

@@ -1,17 +1,18 @@
 package org.everit.json.schema.internal;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNull;
-
-import java.io.StringWriter;
-import java.util.HashMap;
-
 import org.everit.json.schema.NullSchema;
 import org.everit.json.schema.Schema;
 import org.json.JSONObject;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
+import java.io.StringWriter;
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
 public class JSONPrinterTest {
 
     private StringWriter buffer;
@@ -127,10 +128,10 @@ public void arraySupport() {
 
     @Test
     public void printSchemaMap() {
-        HashMap<Number, Schema> input = new HashMap<Number, Schema>();
+        Map<Number, Schema> input = new LinkedHashMap<>();
         input.put(2, NullSchema.INSTANCE);
         subject().printSchemaMap(input);
-        assertEquals("{\"2\":" + NullSchema.INSTANCE.toString() + "}", buffer.toString());
+        assertEquals("{\"2\":" + NullSchema.INSTANCE + "}", buffer.toString());
     }
 
 }