RestTemplateBuilder class

public RestTemplate build() {
		return build(RestTemplate.class);
	}

public <T extends RestTemplate> T build(Class<T> restTemplateClass) {
		return configure(BeanUtils.instantiate(restTemplateClass));
	}
-----
BeanUtils class
public static <T> T instantiate(Class<T> clazz) throws BeanInstantiationException {
		Assert.notNull(clazz, "Class must not be null");
		if (clazz.isInterface()) {
			throw new BeanInstantiationException(clazz, "Specified class is an interface");
		}
		try {
			return clazz.newInstance(); <--- create the instance of the passed class i.e. RestTemplate()
		}
		catch (InstantiationException ex) {
			throw new BeanInstantiationException(clazz, "Is it an abstract class?", ex);
		}
		catch (IllegalAccessException ex) {
			throw new BeanInstantiationException(clazz, "Is the constructor accessible?", ex);
		}
	}