* <p>First, tries to resolve it against a System property ({@link System#getProperty(String)}), next,
* tries and resolve it against an environment variable ({@link System#getenv(String)}), and last, tries
* and replace it with another setting already set on this builder.
*/
public Builder replacePropertyPlaceholders() {
PropertyPlaceholder propertyPlaceholder = new PropertyPlaceholder("${", "}", false);
PropertyPlaceholder.PlaceholderResolver placeholderResolver = new PropertyPlaceholder.PlaceholderResolver() {
@Override
public String resolvePlaceholder(String placeholderName) {
if (placeholderName.startsWith("env.")) {
// explicit env var prefix
return System.getenv(placeholderName.substring("env.".length()));
}
String value = System.getProperty(placeholderName);
if (value != null) {
return value;
}
value = System.getenv(placeholderName);
if (value != null) {
return value;
}
return map.get(placeholderName);
}
@Override
public boolean shouldIgnoreMissing(String placeholderName) {
// if its an explicit env var, we are ok with not having a value for it and treat it as optional
if (placeholderName.startsWith("env.")) {
return true;
}
return false;
}
};
for (Map.Entry<String, String> entry : Maps.newHashMap(map).entrySet()) {
String value = propertyPlaceholder.replacePlaceholders(entry.getValue(), placeholderResolver);
// if the values exists and has length, we should maintain it in the map
// otherwise, the replace process resolved into removing it
if (Strings.hasLength(value)) {
map.put(entry.getKey(), value);
} else {