DFA: remove CAN_BE_NULL fact in removeEquivalenceRelations to allow merging null and not-null vars

Fixes IDEA-184723 Data flow algorithm complexity

java/java-tests/testData/inspection/dataFlow/fixture/OptionalTooComplex.java

@@ -0,0 +1,48 @@
+import java.util.Optional;
+
+// IDEA-184723
+class OptionalTooComplex {
+  // Should not be too complex
+  public Long fetch() {
+    final PreparedStatement ps = builder
+      .setInteger(<warning descr="Argument 'opt().orElse(null)' might be null but passed to non annotated parameter">opt().orElse(null)</warning>)
+      .setInteger(<warning descr="Argument 'opt().orElse(null)' might be null but passed to non annotated parameter">opt().orElse(null)</warning>)
+      .setInteger(<warning descr="Argument 'opt().orElse(null)' might be null but passed to non annotated parameter">opt().orElse(null)</warning>)
+      .setInteger(<warning descr="Argument 'opt().orElse(null)' might be null but passed to non annotated parameter">opt().orElse(null)</warning>)
+      .setInteger(<warning descr="Argument 'opt().orElse(null)' might be null but passed to non annotated parameter">opt().orElse(null)</warning>)
+      .build();
+
+    ResultSet rs = null;
+    try {
+      rs = ps.executeQuery();
+      if (rs.next()) {
+        return rs.getLong();
+      }
+    } catch (final Exception e) {
+      throw new RuntimeException(e);
+    } finally {
+    }
+
+    return 0L;
+  }
+
+  interface ResultSet {
+    boolean next() throws Exception;
+
+    long getLong() throws Exception;
+  }
+
+  interface PreparedStatement {
+    ResultSet executeQuery() throws Exception;
+  }
+
+  native Optional<Integer> opt();
+
+  interface QueryBuilder {
+    QueryBuilder setInteger(Integer value);
+
+    PreparedStatement build();
+  }
+
+  QueryBuilder builder;
+}