Team ID fix in Schedule and Policy importer

[sghosh4-atlassian]

This fixes the following issues during import -

• Updating the schedule with rotation information. Currently it throws the error - Error at updating Schedule Group A_schedule.{"message":"Team with 'id' [{old teamId}] does not exist"}
• Adding a alert policy having a responder team which is different from owner team. Currently it throws the error - Error at adding Policy route to team b. {"message":"Responder does not exist with id:{old teamId}"}

[prakhar-mudaiya]

Will it be possible to have Optional rather than String which would decrease the chance of NPE? If it is not a large task.

[sghosh4-atlassian]

Since the current Java version for this project is set as 1.6, we won't be able to use any Java 8 features. Hence can't really use Optional without updating the java version.

[trabab]

Can we create out own Optional implementation something similar to :

public class Optional<T> {
    private final T value;

    private Optional(T value) {
        this.value = value;
    }

    public static <T> Optional<T> of(T value) {
        if (value == null) {
            throw new NullPointerException("Value cannot be null");
        }
        return new Optional<T>(value);
    }

    public static <T> Optional<T> ofNullable(T value) {
        return new Optional<T>(value);
    }

    public T get() {
        if (value == null) {
            throw new IllegalStateException("Value is not present");
        }
        return value;
    }

    public boolean isPresent() {
        return value != null;
    }

    public T orElse(T defaultValue) {
        return value != null ? value : defaultValue;
    }
}
```       

Usage:

```java
public class Main {
    public static void main(String[] args) {
        Optional<String> stringOptional = Optional.ofNullable(getStringValue());

        if (stringOptional.isPresent()) {
            System.out.println("Value: " + stringOptional.get());
        } else {
            System.out.println("Value not present");
        }
    }

    private static String getStringValue() {
        // Your logic to return a string or null
        return "Hello, World!";
    }
}

[sghosh4-atlassian]

Yeah, something like this can be created. But here also we need to assign null ( Optional.ofNullable(null) ) to create empty objects unlike Java 8 Optional class where we can use Optional.empty().

So the usage of null still can not be completely avoided.

[sghosh4-atlassian]

Added a custom OptionalUtil

[prakhar-mudaiya]

May be if we are using Optional we can send Optional.Empty()

[prakhar-mudaiya]

Do we forsee a case where entity.getSchedule() can be null and this leads to NPE?

[prakhar-mudaiya]

i have a clarifying question is responderTeamName is string? If yes, can we use StringUtils.empty(responderTeamName) otherwise we are good.

[trabab]

can you fix getFileListOf function to return empty list instead of null.

[trabab]

we can get rid of the null check if we address the above comment.