Consider the following case.
----------------------------

jtools-sqe:/home/vr128054/vertest/work 314 % more test.java
public class test
{
        public class test
        {
        }
}

Javadoc runs with a warning on an erraneous class
-------------------------------------------------
jtools-sqe:/home/vr128054/vertest/work 313 % javadoc test.java
Loading source file test.java...
Constructing Javadoc information...
test.java:3: test is already defined in unnamed package
        public class test
               ^
Standard Doclet version 1.4 beta (04 Aug 2001)

Building tree for all the packages and classes...
Building index for all the packages and classes...
Generating overview-tree.html...
Generating index-all.html...
Generating deprecated-list.html...
Building index for all classes...
Generating allclasses-frame.html...
Generating allclasses-noframe.html...
Generating index.html...
Generating packages.html...
Generating test.html...
Generating test.test.html...
Generating package-list...
Generating help-doc.html...
Generating stylesheet.css...
1 warning


JDK1.4 compiler, JDK1.3 Javadoc correctly report a fatal error and stop.