rest-assured/src/main/java/io/restassured/builder/ResponseBuilder.java
public ResponseBuilder setHeader(String name, String value) {
        notNull(name, "Header name");
        notNull(value, "Header value");

        List<Header> newHeaders = new ArrayList<Header>(restAssuredResponse.headers().asList());
        newHeaders.add(new Header(name, value));
        restAssuredResponse.setResponseHeaders(new Headers(newHeaders));

        if (trim(name).equalsIgnoreCase(CONTENT_TYPE)) {
            restAssuredResponse.setContentType(value);
        }
        return this;
    }
public ResponseBuilder setHeader(String name, String value) {
        notNull(name, "Header name");
        notNull(value, "Header value");

        List<Header> newHeaders = new ArrayList<Header>(restAssuredResponse.headers().asList());
        newHeaders.add(new Header(name, value));
        restAssuredResponse.setResponseHeaders(new Headers(newHeaders));

        if (trim(name).equalsIgnoreCase(CONTENT_TYPE)) {
            restAssuredResponse.setContentType(value);
        }
        return this;
    }
Set a specific header

@return The builder