[Solved]-Where is javax.annotation-eclipse

In Java version >= 6, you should not need to add them explicitly.
They are part of the JDK. Just try to skip adding them, maybe
the list of instructions is outdated.

Before Java 6, you would have needed to add this jar, I think: jsr250-api-1.0.jar.

http://central.maven.org/maven2/javax/annotation/jsr250-api/1.0/

http://download.java.net/maven/2/javax/annotation/jsr250-api/1.0/

Javax annotations include in this dependency. This is latest version at the moment.

For maven

<dependency>
<groupId>com.google.code.findbugs</groupId>
<artifactId>jsr305</artifactId>
<version>3.0.2</version>
</dependency>

For gradle

compile('com.google.code.findbugs:jsr305:3.0.2')

Not sure if this is still relevant, but for Java 8, I had to add the two following Maven dependencies in order to get javax.annotation.concurrent.ThreadSafe to work:

    <dependency>
        <groupId>javax.annotation</groupId>
        <artifactId>javax.annotation-api</artifactId>
        <version>1.3.2</version>
    </dependency>

    <dependency>
        <groupId>com.google.code.findbugs</groupId>
        <artifactId>jsr305</artifactId>
        <version>3.0.0</version>
    </dependency> 

Your comment indicates this is for Guava, so you want the JSR305 library, which extends the javax package.

2020 Update: Note that this library breaks the Oracle licensing agreement and Guava has since moved to checkerframework's Nullable annotation.

The dependency including version:

<dependency>
    <groupId>javax.annotation</groupId>
    <artifactId>javax.annotation-api</artifactId>
    <version>1.3.2</version>
</dependency>

See: http://mvnrepository.com/artifact/javax.annotation/javax.annotation-api

Or for the newer jakarta.annotation:

<dependency>
   <groupId>jakarta.annotation</groupId>
   <artifactId>jakarta.annotation-api</artifactId>
   <version>1.3.5</version>
</dependency>

See: https://mvnrepository.com/artifact/jakarta.annotation/jakarta.annotation-api

The Java Common Annotations Module java.xml.ws.annotation was deprecated in Java version 9 and was removed in java version 11. If this leads to a problem you could try to add javax.annotation.

The Javadocs for Java 8 can be found here: http://docs.oracle.com/javase/8/docs/api/javax/annotation/package-summary.html