add equals and hashcode to AFM ExpressionFilter

Author: peter-plochan

src/main/java/com/gooddata/executeafm/afm/ExpressionFilter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2007-2017, GoodData(R) Corporation. All rights reserved.
+ * Copyright (C) 2007-2018, GoodData(R) Corporation. All rights reserved.
  * This source code is licensed under the BSD-style license found in the
  * LICENSE.txt file in the root directory of this source tree.
  */
@@ -10,11 +10,13 @@
 import com.fasterxml.jackson.annotation.JsonRootName;
 import com.gooddata.util.GoodDataToStringBuilder;
 
+import java.util.Objects;
+
 /**
  * To be deprecated filter using plain expression
  */
 @JsonRootName("expression")
-public class ExpressionFilter implements CompatibilityFilter {
+public final class ExpressionFilter implements CompatibilityFilter {
     static final String NAME = "expression";
     private final String value;
 
@@ -27,12 +29,27 @@ public ExpressionFilter(@JsonProperty("value") final String value) {
         this.value = value;
     }
 
-   public String getValue() {
+    public String getValue() {
         return value;
     }
 
     @Override
     public String toString() {
         return GoodDataToStringBuilder.defaultToString(this);
     }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (!(o instanceof ExpressionFilter))
+            return false;
+        ExpressionFilter that = (ExpressionFilter) o;
+        return Objects.equals(value, that.value);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(value);
+    }
 }

src/test/groovy/com/gooddata/executeafm/afm/ExpressionFilterTest.groovy

@@ -1,10 +1,11 @@
 /*
- * Copyright (C) 2007-2017, GoodData(R) Corporation. All rights reserved.
+ * Copyright (C) 2007-2018, GoodData(R) Corporation. All rights reserved.
  * This source code is licensed under the BSD-style license found in the
  * LICENSE.txt file in the root directory of this source tree.
  */
 package com.gooddata.executeafm.afm
 
+import nl.jqno.equalsverifier.EqualsVerifier
 import spock.lang.Specification
 
 import static com.gooddata.util.ResourceUtils.readObjectFromResource
@@ -29,4 +30,9 @@ class ExpressionFilterTest extends Specification {
         filter.value == 'some expression'
         filter.toString()
     }
+
+    def "should verify equals"() {
+        expect:
+        EqualsVerifier.forClass(ExpressionFilter).verify()
+    }
 }