*/
    public static final int TRANSFER_INITIATED = 0;

    /**
     * A transfer was started.
     */
    public static final int TRANSFER_STARTED = 1;

    /**
     * A transfer is completed.
     */
    public static final int TRANSFER_COMPLETED = 2;

    /**
     * A transfer is in progress.
     */
    public static final int TRANSFER_PROGRESS = 3;

    /**

import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * The annotated element must not be null.
 * <p>
 * Annotated fields must not be null after construction has completed.
 * <p>
 * When this annotation is applied to a method it applies to the method return value.
 *
 * @see Nullable
 * @since 4.0.0
 */
@Experimental
@Documented
@Retention(RetentionPolicy.CLASS)

Quick Build
-------
If you want to bootstrap Maven, you'll need:
- Java 17+
- Maven 3.6.3 or later
- Run Maven, specifying a location into which the completed Maven distro should be installed:
    ```
    mvn -DdistributionTargetDir="$HOME/app/maven/apache-maven-4.0.x-SNAPSHOT" clean package
    ```


[home]: https://maven.apache.org/