JavaDoc failures on kokoro

Not immediately obvious why this errors the build on Kokoro and not CircleCI

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-javadoc-plugin:3.2.0:jar (default-cli) on project dependencies: MavenReportException: Error while generating Javadoc:
[ERROR] Exit code: 1 - /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/ClassFile.java:41: warning: no @return
[ERROR] public ClassPathEntry getClassPathEntry() {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/ClassFile.java:50: warning: no @return
[ERROR] public String getBinaryName() {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/ClassPathBuilder.java:63: warning: no @return
[ERROR] public ClassPathResult resolve(List artifacts) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/ClassPathEntry.java:119: warning: no @return
[ERROR] public synchronized ImmutableSet getClassNames() throws IOException {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/ClassPathEntry.java:50: warning: no @param for artifact
[ERROR] public ClassPathEntry(Artifact artifact) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/ClassPathResult.java:60: warning: no @return
[ERROR] public ImmutableList getClassPath() {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/ClassPathResult.java:68: warning: no @param for entry
[ERROR] public ImmutableList getDependencyPaths(ClassPathEntry entry) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/ClassPathResult.java:68: warning: no @return
[ERROR] public ImmutableList getDependencyPaths(ClassPathEntry entry) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/ClassPathResult.java:73: warning: no @return
[ERROR] public ImmutableList getArtifactProblems() {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/ClassPathResult.java:78: warning: no @param for entries
[ERROR] public String formatDependencyPaths(Iterable entries) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/ClassPathResult.java:78: warning: no @return
[ERROR] public String formatDependencyPaths(Iterable entries) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/ClassPathResult.java:101: warning: no @return
[ERROR] public ImmutableSetMultimap coordinatesToClassPathEntry() {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/ClassReferenceGraph.java:84: warning: no @param for className
[ERROR] public boolean isReachable(String className) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/ClassReferenceGraph.java:84: warning: no @return
[ERROR] public boolean isReachable(String className) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/ErrorType.java:71: warning: no @param for subject
[ERROR] public String getMessage(String subject) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/ErrorType.java:71: warning: no @return
[ERROR] public String getMessage(String subject) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/LinkageChecker.java:79: warning: no @return
[ERROR] public static LinkageChecker create(
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/LinkageChecker.java:79: warning: no @throws for java.io.IOException
[ERROR] public static LinkageChecker create(
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/LinkageChecker.java:140: error: unknown tag: returns
[ERROR] * @returns {@link SymbolProblem}s found in the class path and referencing classes
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/LinkageChecker.java:143: warning: no @return
[ERROR] public ImmutableSetMultimap findSymbolProblems() throws IOException {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/SymbolProblem.java:65: warning: no @return
[ERROR] public ClassFile getContainingClass() {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/ArtifactProblem.java:52: warning: no @return
[ERROR] protected String getPath() {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/ArtifactProblem.java:57: warning: no @return
[ERROR] public Artifact getArtifact() {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/ArtifactProblem.java:64: warning: no @param for problems
[ERROR] public static String formatProblems(Iterable problems) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/ArtifactProblem.java:64: warning: no @return
[ERROR] public static String formatProblems(Iterable problems) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/Artifacts.java:33: warning: no @param for artifact
[ERROR] public static String toCoordinates(Artifact artifact) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/Artifacts.java:33: warning: no @return
[ERROR] public static String toCoordinates(Artifact artifact) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/Bom.java:45: warning: no @return
[ERROR] public ImmutableList getManagedDependencies() {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/Bom.java:52: warning: no @return
[ERROR] public String getCoordinates() {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/DependencyGraph.java:102: warning: no @param for coordinates
[ERROR] public Set getPaths(String coordinates) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/DependencyGraph.java:109: warning: no @return
[ERROR] public List findUpdates() {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/DependencyGraphBuilder.java:179: warning: no @param for dependency
[ERROR] public DependencyGraphResult buildMavenDependencyGraph(Dependency dependency) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/DependencyGraphBuilder.java:179: warning: no @return
[ERROR] public DependencyGraphResult buildMavenDependencyGraph(Dependency dependency) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/DependencyGraphBuilder.java:213: warning: no @param for dependencyGraph
[ERROR] public static UnresolvableArtifactProblem createUnresolvableArtifactProblem(
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/DependencyGraphBuilder.java:213: warning: no @param for artifact
[ERROR] public static UnresolvableArtifactProblem createUnresolvableArtifactProblem(
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/DependencyGraphBuilder.java:213: warning: no @return
[ERROR] public static UnresolvableArtifactProblem createUnresolvableArtifactProblem(
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/DependencyGraphResult.java:40: warning: no @return
[ERROR] public ImmutableList getArtifactProblems() {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/DependencyPath.java:44: warning: no @return
[ERROR] public int size() {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/DependencyPath.java:49: warning: no @return
[ERROR] public Artifact getLeaf() {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/DependencyPath.java:54: warning: no @return
[ERROR] public ImmutableList getArtifacts() {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/DependencyPath.java:62: warning: no @param for i
[ERROR] public Artifact get(int i) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/DependencyPath.java:62: warning: no @return
[ERROR] public Artifact get(int i) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:103: warning: no @return
[ERROR] public static RepositorySystem newRepositorySystem() {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:126: warning: no @param for system
[ERROR] public static DefaultRepositorySystemSession newSession(RepositorySystem system) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:126: warning: no @return
[ERROR] public static DefaultRepositorySystemSession newSession(RepositorySystem system) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:250: warning: no @param for coordinates
[ERROR] public static Bom readBom(String coordinates) throws ArtifactDescriptorException {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:250: warning: no @return
[ERROR] public static Bom readBom(String coordinates) throws ArtifactDescriptorException {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:250: warning: no @throws for org.eclipse.aether.resolution.ArtifactDescriptorException
[ERROR] public static Bom readBom(String coordinates) throws ArtifactDescriptorException {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:259: warning: no @param for coordinates
[ERROR] public static Bom readBom(String coordinates, List mavenRepositoryUrls)
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:259: warning: no @return
[ERROR] public static Bom readBom(String coordinates, List mavenRepositoryUrls)
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:259: warning: no @throws for org.eclipse.aether.resolution.ArtifactDescriptorException
[ERROR] public static Bom readBom(String coordinates, List mavenRepositoryUrls)
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:301: warning: no @param for artifact
[ERROR] public static boolean shouldSkipBomMember(Artifact artifact) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:301: warning: no @return
[ERROR] public static boolean shouldSkipBomMember(Artifact artifact) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:326: warning: no @param for mavenRepositoryUrl
[ERROR] public static RemoteRepository mavenRepositoryFromUrl(String mavenRepositoryUrl) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:326: warning: no @return
[ERROR] public static RemoteRepository mavenRepositoryFromUrl(String mavenRepositoryUrl) {
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:382: warning: no @param for repositorySystem
[ERROR] public static ImmutableList findVersions(
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:382: warning: no @param for groupId
[ERROR] public static ImmutableList findVersions(
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:382: warning: no @param for artifactId
[ERROR] public static ImmutableList findVersions(
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:382: warning: no @return
[ERROR] public static ImmutableList findVersions(
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:382: warning: no @throws for com.google.cloud.tools.opensource.dependencies.MavenRepositoryException
[ERROR] public static ImmutableList findVersions(
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:396: warning: no @param for repositorySystem
[ERROR] public static String findLatestCoordinates(
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:396: warning: no @param for groupId
[ERROR] public static String findLatestCoordinates(
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:396: warning: no @param for artifactId
[ERROR] public static String findLatestCoordinates(
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:396: warning: no @return
[ERROR] public static String findLatestCoordinates(
[ERROR] ^
[ERROR] /Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/src/main/java/com/google/cloud/tools/opensource/dependencies/RepositoryUtility.java:396: warning: no @throws for com.google.cloud.tools.opensource.dependencies.MavenRepositoryException
[ERROR] public static String findLatestCoordinates(
[ERROR] ^
[ERROR]
[ERROR] Command line was: /Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/../bin/javadoc @options @packages
[ERROR]

[ERROR] Refer to the generated Javadoc files in '/Volumes/BuildData/tmpfs/src/github/cloud-opensource-java/dependencies/target/apidocs' dir.
[ERROR] -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
[ERROR]
[ERROR] After correcting the problems, you can resume the build with the command
[ERROR] mvn -rf :dependencies