private boolean getReturnsNullability(boolean nullsExpected) {
    PsiElement body = null;
    if (myCodeFragmentMember instanceof PsiParameterListOwner) {
      body = ((PsiParameterListOwner)myCodeFragmentMember).getBody();
    }
    if (body == null) return false;

    Set<PsiExpression> returnedExpressions = StreamEx.of(myExitStatements)
      .select(PsiReturnStatement.class)
      .map(PsiReturnStatement::getReturnValue)
      .nonNull()
      .toSet();

    for (Iterator<PsiExpression> it = returnedExpressions.iterator(); it.hasNext(); ) {
      PsiType type = it.next().getType();
      if (nullsExpected) {
        if (type == PsiTypes.nullType()) {
          it.remove(); // don't need to check
        }
        else if (type instanceof PsiPrimitiveType) {
          return false;
        }
      }
      else {
        if (type == PsiTypes.nullType()) {
          return false;
        }
        else if (type instanceof PsiPrimitiveType) {
          it.remove(); // don't need to check
        }
      }
    }
    if (returnedExpressions.isEmpty()) return true;

    final var dfaRunner = new StandardDataFlowRunner(myProject);
    final var returnChecker = new JavaDfaListener() {
      @Override
      public void beforeValueReturn(@NotNull DfaValue value,
                                    @Nullable PsiExpression expression,
                                    @NotNull PsiElement context,
                                    @NotNull DfaMemoryState state) {
        if (context == myCodeFragmentMember && expression != null &&
            returnedExpressions.stream().anyMatch(ret -> PsiTreeUtil.isAncestor(ret, expression, false))) {
          DfaNullability nullability = DfaNullability.fromDfType(state.getDfType(value));
          boolean result = nullability == (nullsExpected ? DfaNullability.NULL : DfaNullability.NOT_NULL);
          if (!result) {
            dfaRunner.cancel();
          }
        }
      }
    };
    return dfaRunner.analyzeMethod(body, returnChecker) == RunnerResult.OK;
  }
private boolean getReturnsNullability(boolean nullsExpected)