Fixed NPE warnings

coordination/src/main/java/tech/ydb/coordination/impl/SessionImpl.java

@@ -391,7 +391,7 @@ private class LeaseCreator implements Function<Result<Boolean>, Result<Semaphore
         @Override
         public Result<SemaphoreLease> apply(Result<Boolean> acquireResult) {
             if (!acquireResult.isSuccess()) {
-                return acquireResult.map(null);
+                return acquireResult.map(l -> null);
             }
             if (!acquireResult.getValue()) {
                 return Result.fail(Status.of(StatusCode.TIMEOUT));

core/src/main/java/tech/ydb/core/Result.java

@@ -20,13 +20,13 @@ public interface Result<T> {
     T getValue() throws UnexpectedResultException;
 
     @Nonnull
-    <U> Result<U> map(Function<T, U> mapper);
+    <U> Result<U> map(@Nonnull Function<T, U> mapper);
 
     @Nonnull
-    <U> CompletableFuture<Result<U>> mapResultFuture(Function<T, CompletableFuture<Result<U>>> mapper);
+    <U> CompletableFuture<Result<U>> mapResultFuture(@Nonnull Function<T, CompletableFuture<Result<U>>> mapper);
 
     @Nonnull
-    CompletableFuture<Status> mapStatusFuture(Function<T, CompletableFuture<Status>> mapper);
+    CompletableFuture<Status> mapStatusFuture(@Nonnull Function<T, CompletableFuture<Status>> mapper);
 
     default boolean isSuccess() {
         return getStatus().getCode() == StatusCode.SUCCESS;

core/src/main/java/tech/ydb/core/impl/BaseGrpcTransport.java

@@ -67,7 +67,7 @@ public <ReqT, RespT> CompletableFuture<Result<RespT>> unaryCall(
             ReqT request
     ) {
         if (isClosed.get()) {
-            return CompletableFuture.completedFuture(SHUTDOWN_RESULT.map(null));
+            return CompletableFuture.completedFuture(SHUTDOWN_RESULT.map(o -> null));
         }
 
         String traceId = settings.getTraceId();

core/src/main/java/tech/ydb/core/operation/OperationBinder.java

@@ -53,7 +53,7 @@ public static <R, M extends Message> Function<Result<R>, Result<M>> bindSync(
     ) {
         return (result) -> {
             if (!result.isSuccess()) {
-                return result.map(null);
+                return result.map(r -> null);
             }
             OperationProtos.Operation operation = method.apply(result.getValue());
             if (!operation.getReady()) {

query/src/main/java/tech/ydb/query/tools/SessionRetryContext.java

@@ -262,7 +262,7 @@ StatusCode toStatusCode(Result<T> result) {
 
         @Override
         Result<T> toFailedResult(Result<QuerySession> sessionResult) {
-            return sessionResult.map(null);
+            return sessionResult.map(s -> null);
         }
     }
 

table/src/main/java/tech/ydb/table/SessionRetryContext.java

@@ -287,7 +287,7 @@ StatusCode toStatusCode(Result<T> result) {
 
         @Override
         Result<T> toFailedResult(Result<Session> sessionResult) {
-            return sessionResult.map(null);
+            return sessionResult.map(s -> null);
         }
     }
 

table/src/main/java/tech/ydb/table/impl/BaseSession.java

@@ -751,7 +751,7 @@ private static ChangefeedDescription.State mapChangefeedState(YdbTable.Changefee
     private static Result<TableDescription> mapDescribeTable(Result<YdbTable.DescribeTableResult> describeResult,
             DescribeTableSettings settings) {
         if (!describeResult.isSuccess()) {
-            return describeResult.map(null);
+            return describeResult.map(r -> null);
         }
         YdbTable.DescribeTableResult desc = describeResult.getValue();
         SchemeOperationProtos.Entry.Type entryType = desc.getSelf().getType();
@@ -900,7 +900,7 @@ private static YdbTable.TransactionSettings txSettings(Transaction.Mode transact
     private static Result<TableOptionDescription> mapDescribeTableOptions(
             Result<YdbTable.DescribeTableOptionsResult> describeTableOptionsResult) {
         if (!describeTableOptionsResult.isSuccess()) {
-            return describeTableOptionsResult.map(null);
+            return describeTableOptionsResult.map(r -> null);
         }
 
         YdbTable.DescribeTableOptionsResult describeResult = describeTableOptionsResult.getValue();