A DESCRIPTION OF THE PROBLEM :
The Javadoc tool doesn't properly generate the Javadoc when {@summary} tag is not used first. Also with certain HTML elements, the same behavior can be obtained.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Make a test class in any package (Here I have used TestP package), add Javadoc to the top class. Generate the Javadoc using CLI or any in IDE tool if you use it.
I can't attach screenshots as proof otherwise I would have.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The summary for the class - The first line doesn't end with a period

The summary for the method - The first line doesn't end with a period
ACTUAL -
The summary for the class - The first line doesn't end with a period This will be included in summary when it shouldn't be.

The summary for the method - The first line doesn't end with a period

---------- BEGIN SOURCE ----------
package TestP;

/**
 * The first line doesn't end with a period
 * {@summary This will be included in summary when it shouldn't be.}
 */
public class Test {

    /**
     * <p>The first line doesn't end with a period</p>
     * {@summary This will be not be included in summary.}
     */
    public void method() {
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
As a workaround for now, if you add a period at the end of the top sentence, the contents of the summary tag are not included in the actual Javadoc summary.

FREQUENCY : always