public boolean shouldOverwriteHeaderWithName(String headerName) {
        notNull(headerName, "Header name");
        return headersToOverwrite.get(headerName.toUpperCase());
    }
@Test public void
    accept_header_is_overwritable_by_default() {
        HeaderConfig headerConfig = new HeaderConfig();

        assertThat(headerConfig.shouldOverwriteHeaderWithName("content-type"), is(true));
    }