Harden Fraction.readObject() to reject bad cached hash code (#1634)

Author: garydgregory

src/changes/changes.xml

@@ -137,6 +137,7 @@ java.lang.NullPointerException: Cannot invoke
     <action issue="LANG-879"  type="fix" dev="ggregory" due-to="Matthew T. Adams, Gary Gregory">LocaleUtils test fails with new Locale "ja_JP_JP_#u-ca-japanese" of JDK7.</action>
     <action                   type="fix" dev="ggregory" due-to="Omkhar Arasaratnam, Gary Gregory">Fix typo in SystemProperties.JDK_XML_ENTITY_REPLACEMENT_LIMIT (#1631).</action>
     <action                   type="fix" dev="ggregory" due-to="Omkhar Arasaratnam, Gary Gregory">Harden Range.readObject() to reject bad cached hash code (#1633).</action>
+    <action                   type="fix" dev="ggregory" due-to="Omkhar Arasaratnam, Gary Gregory">Harden Fraction.readObject() to reject bad cached hash code (#1634).</action>
     <!-- ADD -->
     <action                   type="add" dev="ggregory" due-to="Gary Gregory">Add JavaVersion.JAVA_27.</action>
     <action                   type="add" dev="ggregory" due-to="Gary Gregory">Add SystemUtils.IS_JAVA_27.</action>