Unused erasure anchor tag is written in
jdk.javadoc.internal.doclets.formats.html.ConstructorWriterImpl.getConstructorDocTreeHeader() and
jdk.javadoc.internal.doclets.formats.html.MethodWriterImpl.getMethodDocTreeHeader():

public Content getConstructorDocTreeHeader(ExecutableElement constructor, Content constructorDetailsTree) {
        String erasureAnchor;
        if ((erasureAnchor = getErasureAnchor(constructor)) != null) {
            constructorDetailsTree.addContent(writer.getMarkerAnchor((erasureAnchor)));
        }
.................

public Content getMethodDocTreeHeader(ExecutableElement method, Content methodDetailsTree) {
        String erasureAnchor;
        if ((erasureAnchor = getErasureAnchor(method)) != null) {
            methodDetailsTree.addContent(writer.getMarkerAnchor((erasureAnchor)));
        }
.................