FULL PRODUCT VERSION :
The Optional class is introduced in Java 8. As of yesterday (3/18/2015), the Javadoc issue remained unfixed in the latest Java 9 sources.

ADDITIONAL OS VERSION INFORMATION :
This is not OS-specific - it is a bug in the Javadoc for the java.util.Optional class.

A DESCRIPTION OF THE PROBLEM :
https://docs.oracle.com/javase/8/docs/api/java/util/Optional.html#equals-java.lang.Object-

The generated Javadoc says:

Returns:
    {code true} if the other object is "equal to" this object otherwise false

Notice the '{code true}'. This is a simple typo, it should've been:

   {@code true}

ADDITIONAL REGRESSION INFORMATION:
Not a regression, since this is a class new to Java 8.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Navigate to the public Javadoc page for the java.util.Optional class
2. Go to the documentation for the equals() method
3. Observe '{code true}' in the Returns section, instead of just 'true'

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The 'true' keyword formatted as code.
ACTUAL -
{code true}, which is a typo from the intended {@code true}

REPRODUCIBILITY :
This bug can be reproduced always.