public String getStatData()

in core/src/main/java/hudson/model/UsageStatistics.java [126:195]
59 lines of code
10 McCabe index (conditional complexity)

    public String getStatData() throws IOException {
        Jenkins j = Jenkins.get();

        JSONObject o = new JSONObject();
        o.put("stat",1);
        o.put("install", j.getLegacyInstanceId());
        o.put("servletContainer", j.servletContext.getServerInfo());
        o.put("version", Jenkins.VERSION);

        List<JSONObject> nodes = new ArrayList<>();
        for( Computer c : j.getComputers() ) {
            JSONObject  n = new JSONObject();
            if(c.getNode()==j) {
                n.put("master",true);
                n.put("jvm-vendor", System.getProperty("java.vm.vendor"));
                n.put("jvm-name", System.getProperty("java.vm.name"));
                n.put("jvm-version", System.getProperty("java.version"));
            }
            n.put("executors",c.getNumExecutors());
            DescriptorImpl descriptor = j.getDescriptorByType(DescriptorImpl.class);
            n.put("os", descriptor.get(c));
            nodes.add(n);
        }
        o.put("nodes",nodes);

        List<JSONObject> plugins = new ArrayList<>();
        for( PluginWrapper pw : j.getPluginManager().getPlugins() ) {
            if(!pw.isActive())  continue;   // treat disabled plugins as if they are uninstalled
            JSONObject p = new JSONObject();
            p.put("name",pw.getShortName());
            p.put("version",pw.getVersion());
            plugins.add(p);
        }
        o.put("plugins",plugins);

        JSONObject jobs = new JSONObject();
        // capture the descriptors as these should be small compared with the number of items
        // so we will walk all items only once and we can short-cut the search of descriptors
        TopLevelItemDescriptor[] descriptors = Items.all().toArray(new TopLevelItemDescriptor[0]);
        int[] counts = new int[descriptors.length];
        for (TopLevelItem item: j.allItems(TopLevelItem.class)) {
            TopLevelItemDescriptor d = item.getDescriptor();
            for (int i = 0; i < descriptors.length; i++) {
                if (d == descriptors[i]) {
                    counts[i]++;
                    // no point checking any more, we found the match
                    break;
                }
            }
        }
        for (int i = 0; i < descriptors.length; i++) {
            jobs.put(descriptors[i].getJsonSafeClassName(), counts[i]);
        }
        o.put("jobs",jobs);

        try {
            ByteArrayOutputStream baos = new ByteArrayOutputStream();

            // json -> UTF-8 encode -> gzip -> encrypt -> base64 -> string
            try (OutputStream cipheros = new CombinedCipherOutputStream(baos,getKey(),"AES");
                 OutputStream zipos = new GZIPOutputStream(cipheros);
                 OutputStreamWriter w = new OutputStreamWriter(zipos, StandardCharsets.UTF_8)) {
                o.write(w);
            }

            return new String(Base64.getEncoder().encode(baos.toByteArray()));
        } catch (GeneralSecurityException e) {
            throw new Error(e); // impossible
        }
    }