[java] Verify fix for BrokenNullCheck (#718)

Closes #718

docs/pages/release_notes.md

@@ -140,6 +140,7 @@ in the Migration Guide.
 * java-design
   * [#174](https://github.com/pmd/pmd/issues/174):   \[java] SingularField false positive with switch in method that both assigns and reads field
 * java-errorprone
+  * [#718](https://github.com/pmd/pmd/issues/718):   \[java] BrokenNullCheck false positive with parameter/field confusion
   * [#1831](https://github.com/pmd/pmd/issues/1831): \[java] DetachedTestCase reports abstract methods
   * [#4719](https://github.com/pmd/pmd/pull/4719):   \[java] UnnecessaryCaseChange: example doc toUpperCase() should compare to a capitalized string
 * javascript
@@ -763,6 +764,7 @@ Language specific fixes:
     * [#4416](https://github.com/pmd/pmd/pull/4416):   \[java] Fix reported line number in CommentContentRule
 * java-errorprone
     * [#659](https://github.com/pmd/pmd/issues/659):   \[java] MissingBreakInSwitch - last default case does not contain a break
+    * [#718](https://github.com/pmd/pmd/issues/718):   \[java] BrokenNullCheck false positive with parameter/field confusion
     * [#1005](https://github.com/pmd/pmd/issues/1005): \[java] CloneMethodMustImplementCloneable triggers for interfaces
     * [#1669](https://github.com/pmd/pmd/issues/1669): \[java] NullAssignment - FP with ternay and null as constructor argument
     * [#1831](https://github.com/pmd/pmd/issues/1831): \[java] DetachedTestCase reports abstract methods

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/errorprone/xml/BrokenNullCheck.xml

@@ -364,4 +364,44 @@ public class Library {
             }
             ]]></code>
     </test-code>
+    <test-code>
+        <description>[java] BrokenNullCheck false positive with parameter/field confusion #718 - Part 1</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+public class PmdTest {
+    public static boolean test1(final boolean hasFoo, final boolean hasBar, final Object foo, final Object bar) {
+        final boolean hasFooObject = foo != null;
+        final boolean hasBarObject = bar != null;
+        if (hasFoo == hasFooObject && hasBar == hasBarObject) {
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    public static boolean test2(final boolean hasFoo, final boolean hasBar, final Object foo, final Object bar) {
+        if (hasFoo == (foo != null) && hasBar == (bar != null)) {
+            return true;
+        } else {
+            return false;
+        }
+    }
+}
+]]></code>
+    </test-code>
+    <test-code>
+        <description>[java] BrokenNullCheck false positive with parameter/field confusion #718 - Part 2</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+public class PmdTest2 {
+  private Boolean f;
+
+  // parameter of the same name as field
+  public void f(Boolean f) {
+    if (f != null || this.f == null)
+      ;
+  }
+}
+        ]]></code>
+    </test-code>
 </test-data>