/**
 * Copyright 2016 Yahoo Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.yahoo.pulsar.broker;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.net.InetAddress;
import java.net.UnknownHostException;

public class ServiceConfigurationUtils {

    private static final Logger LOG = LoggerFactory.getLogger(ServiceConfigurationUtils.class);

    public static String getDefaultOrConfiguredAddress(String configuredAddress) {
        if ( configuredAddress == null ) {
            return unsafeLocalhostResolve();
        }
        return configuredAddress;
    }

    public static String unsafeLocalhostResolve() {
        try {
            return InetAddress.getLocalHost().getHostName();
        } catch (UnknownHostException ex) {
            LOG.error(ex.getMessage(), ex);
            throw new IllegalStateException("Failed to resolve localhost name.", ex);
        }
    }

}

/**
 * Copyright 2016 Yahoo Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.yahoo.pulsar.broker;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.net.InetAddress;
import java.net.UnknownHostException;

import static org.apache.commons.lang3.StringUtils.isBlank;

public class ServiceConfigurationUtils {

    private static final Logger LOG = LoggerFactory.getLogger(ServiceConfigurationUtils.class);

    public static String getDefaultOrConfiguredAddress(String configuredAddress) {
        if (isBlank(configuredAddress)) {
            return unsafeLocalhostResolve();
        }
        return configuredAddress;
    }

    public static String unsafeLocalhostResolve() {
        try {
            return InetAddress.getLocalHost().getHostName();
        } catch (UnknownHostException ex) {
            LOG.error(ex.getMessage(), ex);
            throw new IllegalStateException("Failed to resolve localhost name.", ex);
        }
    }

}

Revise null check of ServiceConfigureUtils (#47)