@Contract("_, !null -> !null")
    public String getUserProperty(@NotNull final String propertyName, @Nullable final String defaultValue) {
        return this.userProperties.get(propertyName) != null
            ? (String) this.userProperties.get(propertyName)
            : defaultValue;
    }
Gets a configured setting from <code>~/.testcontainers.properties</code>.

@param propertyName name of configuration file property (dot-separated lower case)
@return the found value, or null if not set
core/src/main/java/org/testcontainers/utility/TestcontainersConfiguration.java