Override hashCode where equals is overridden

If two objects are equal according to the equals(Object), then calling
the hashCode method on each of the two objects must produce the same
integer result.

However we have classes in src/tests that overrides equals(Object)
without overriding the hashCode method. This overrides the missing
hashCode methods.

Fixes: #85

src/tests/TypeNameTest.java

@@ -45,6 +45,11 @@ public boolean equals(Object other) {
     return ((B) other).data == data;
   }
 
+  @Override
+  public int hashCode() {
+    return Integer.hashCode(data);
+  }
+
   @Override
   public String toString() {
     return "B {data=" + data + "}";

src/tests/gov/nasa/jpf/test/mc/data/CGCreatorFactoryTest.java

@@ -56,6 +56,10 @@ public boolean equals(Object o) {
       return this.b == other.b;
     }
 
+    @Override
+    public int hashCode() {
+        return Boolean.hashCode(b);
+    }
   }
 
   @Test

src/tests/gov/nasa/jpf/test/mc/data/JSONTest.java

@@ -23,6 +23,9 @@
 
 import org.junit.Test;
 
+import java.util.Arrays;
+import java.util.Objects;
+
 
 /**
  * JPF regression test for JSON test object creation
@@ -350,6 +353,11 @@ public boolean equals(Object o) {
       Bool bool = (Bool) o;
       return this.b == bool.b;
     }
+
+    @Override
+    public int hashCode() {
+      return Boolean.hashCode(b);
+    }
   }
 
   static void checkValue(Object[] expected, Object curVal) {
@@ -399,6 +407,11 @@ public boolean equals(Object o) {
 
       return bs.b == b && bs.s == s && bs.i == i && bs.l == l;
     }
+
+    @Override
+    public int hashCode() {
+      return Objects.hash(b, s, i, l);
+    }
   }
 
   @Test
@@ -457,6 +470,11 @@ public boolean equals(Object o) {
 
       return outer.inner.i == this.inner.i;
     }
+
+    @Override
+    public int hashCode() {
+      return inner.i;
+    }
   }
 
   @Test
@@ -498,6 +516,11 @@ public boolean equals(Object o) {
       }
       return true;
     }
+
+    @Override
+    public int hashCode() {
+      return Arrays.hashCode(arr);
+    }
   }
 
   @Test
@@ -529,6 +552,11 @@ public boolean equals(Object obj) {
       BoxedInteger bic = (BoxedInteger) obj;
       return this.bi.equals(bic.bi);
     }
+
+    @Override
+    public int hashCode() {
+      return bi;
+    }
   }
 
   @Test
@@ -565,6 +593,11 @@ boolean doublesEqual(double d1, double d2) {
 
       return Math.abs(d1 - d2) <= diff;
     }
+
+    @Override
+    public int hashCode() {
+      return Double.hashCode(d);
+    }
   }
 
   @Test

src/tests/gov/nasa/jpf/util/SortedArrayObjectSetTest.java

@@ -21,6 +21,8 @@
 import gov.nasa.jpf.util.test.TestJPF;
 import org.junit.Test;
 
+import java.util.Objects;
+
 
 /**
  * regression test for SortedArrayObjectSet
@@ -59,6 +61,11 @@ public boolean equals(Object o){
 
       return false;
     }
+
+    @Override
+    public int hashCode() {
+      return Objects.hash(id, x);
+    }
   }
 
   @Test