REST API endpoints can be obtained using:
endpoints <- sapply(h2o.api("GET /3/Metadata/endpoints")$routes, function(r) paste(r$http_method, r$url_pattern))
For a given route, the supported params can be otained using:
parameters <- sapply(h2o.api("GET /3/Metadata/schemas/{route$input_schema}")$schemas[[1]]$fields, function(f) { l <-list(); l[f$name] <- f$help; l })