[Demonstration 1]

[Buggy Method]
static String filterInputCharacters(String str) {
    char[] array = str.toCharArray();
    StringBuilder result = new StringBuilder();
    for (char ch : array) {
        if ((ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z') || (ch >= '0' && ch <= '9')) {
            result.append(ch);
        }
    }
    return result.toString();
}

[Buggy Hunk]
static String filterInputCharacters(String str) {

[Patch]
public static String filterInputCharacters(String str) {

[Demonstration 2]

[Buggy Method]
public MetadataMessageBuilder getBuilderForType(final MetadataMessageBuilder builder, String branch) {
    final boolean isDeprecated = javaType.hasAnnotation(Deprecated.class);
    builder.appendContent("`" + getTypeType() + "` ");
    builder.appendContent((isDeprecated ? "~~" : "") + "`" + javaType.getQualifiedName() + "`" + (isDeprecated ? "~~" : "") + "\n");
    EmbedBuilder embed = new EmbedBuilder().ignoreNullEmptyFields().withFooterText("Branch: " + branch);
    embed.withAuthorName(javaType.getName());
    embed.withAuthorIcon(getTypeIcon());
    if (javaType instanceof Extendable) {
        Extendable<?> jt = (Extendable) javaType;
        if (jt.getSuperType() != null) {
            embed.appendField("Extends", "`" + jt.getSuperType() + "`", false);
        }
    }
    if (javaType instanceof InterfaceCapable) {
        InterfaceCapable jt = (InterfaceCapable) javaType;
        if (jt.getInterfaces().size() > 0) {
            embed.appendField("Implements", jt.getInterfaces().stream().collect(Collectors.joining("\n", "`", "`")), false);
        }
    }
    addJavaDocFields(embed, javaType.getJavaDoc());
    {
        MethodHolder<?> methodHolder = (MethodHolder<?>) javaType;
        String desc = "Found " + methodHolder.getMethods().size() + " method" + (methodHolder.getMethods().size() == 1 ? "" : "s") + "\n";
        if (methodHolder.getMethods().size() > 16) {
        }
        int index = 0;
        for (Method m : methodHolder.getMethods()) {
            desc += "`";
            desc += m.getName();
            desc += getMethodParams(m, false);
            desc += " : ";
            desc += (m.getReturnType() == null ? (m.isConstructor() ? "constructor" : "void") : m.getReturnType().toString());
            desc += "`";
            desc += "\n";
            index++;
            if (index % 10 == 0 || index == methodHolder.getMethods().size() - 1) {
                embed.appendField("Methods" + (index > 10 ? " (cont.)" : ""), desc, false);
                desc = "";
            }
        }
    }
    builder.withEmbed(embed.build());
    return builder;
}

[Buggy Hunk]
desc += (m.getReturnType() == null

[Patch]
desc += (m.getReturnType() == null || m.getReturnType().getQualifiedNameWithGenerics().endsWith("void")

[Demonstration 3]

[Buggy Method]
public static Result service(String ownerName, String projectName, String service, boolean isAdvertise) throws IOException, UnsupportedOperationException, ServletException {
    if (!isSupportedService(service)) {
        return forbidden(String.format("Unsupported service: '%s'", service));
    }
    Project project = Project.findByOwnerAndProjectName(ownerName, projectName);
    if (project == null) {
        return notFound();
    }
    models.User user = UserApp.currentUser();
    if (!isAllowed(project, service)) {
        if (user.isAnonymous()) {
            return BasicAuthAction.unauthorized(response());
        } else {
            // If you want the Git client showing your custom message to
            // the user, the Content-Type should be exact "text/plain"
            // without any parameter. For more details, see the code at
            // https://github.com/git/git/commit/426e70d4a11ce3b4f70636d57c6a0ab16ae08a00#diff-eea0ad565ec5903a11b6023755d491cfR154
            response().setHeader("Content-Type", "text/plain");
            return forbidden(String.format("'%s' has no permission to '%s/%s'.", user.name, ownerName, projectName));
        }
    }
    if (isAdvertise) {
        return ok(RepositoryService.gitAdvertise(project, service, response()));
    } else {
        if (request().body().isMaxSizeExceeded()) {
            return status(REQUEST_ENTITY_TOO_LARGE);
        } else {
            user.visits(project);
            return ok(RepositoryService.gitRpc(project, service, request(), response()));
        }
    }
}

[Buggy Hunk]
user.name, ownerName, projectName));

[Patch]
user.loginId, ownerName, projectName));