Revert incorrect fixes for IDEA-184723 Data flow algorithm complexity

This reverts commits 9a837e70d3 and 6d52b5462e.

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/StateMerger.java

@@ -665,10 +665,6 @@ class StateMerger {
 
     @Override
     void removeFromState(@NotNull DfaMemoryStateImpl state) {
-      if(!myPositive && state.isNotNull(myVar) && state.isNull(myArg)) {
-        // merging "x == null" and "x != null" should be possible with marking "x" as nullable
-        state.forceVariableFact(myVar, CAN_BE_NULL, true);
-      }
       state.removeEquivalenceRelations(myVar);
     }
   }

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

@@ -1,31 +0,0 @@
-import org.jetbrains.annotations.*;
-
-class NullabilityBasics {
-
-  void test2() {
-    String x = getNullable();
-    if (x == null) {
-      System.out.println("x is null!");
-    }
-    if (isEmpty(x) && Math.random() > 0.5) {
-      return;
-    }
-    System.out.println(x.<warning descr="Method invocation 'trim' may produce 'java.lang.NullPointerException'">trim</warning>());
-  }
-
-  @Nullable String getNullable() {
-    return Math.random() > 0.5 ? null : "";
-  }
-
-  @Contract(value = "null -> true",pure = true)
-  static boolean isEmpty(@Nullable String s) {
-    return s == null || s.isEmpty();
-  }
-
-  void test(String x) {
-    if (x == null) {
-      System.out.println("x is null!");
-    }
-    System.out.println(x.<warning descr="Method invocation 'trim' may produce 'java.lang.NullPointerException'">trim</warning>());
-  }
-}

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

@@ -1,48 +0,0 @@
-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;
-}

java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection8Test.java

@@ -220,6 +220,4 @@ public class DataFlowInspection8Test extends DataFlowInspectionTestCase {
   public void testPrimitiveGetters() { doTest(); }
   public void testUnknownOnStack() { doTest(); }
   public void testMapUpdateInlining() { doTestWithCustomAnnotations(); }
-
-  public void testOptionalTooComplex() { doTest(); }
 }

java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspectionTest.java

@@ -582,6 +582,5 @@ public class DataFlowInspectionTest extends DataFlowInspectionTestCase {
   public void testPrimitiveNull() { doTest(); }
   public void testLessThanRelations() { doTest(); }
   public void testAdvancedArrayAccess() { doTest(); }
-  public void testNullabilityBasics() { doTest(); }
   public void testNullableGetterInLoop() { doTest(); }
 }