+m4_define(<:APPLY_HEADER_CHANGES:>,
+ <:headers_add = m4_ifelse(<:$1:>, <::>,
+ <:$acl_m_hdradd:>,
+ <:${if def:acl_m_hdradd{$acl_m_hdradd\n}}\
+ $1:>)
+ headers_remove = m4_ifelse(<:$2:>, <::>,
+ <:$acl_m_hdrrm:>,
+ <:${if def:acl_m_hdrrm{$acl_m_hdrrm:}}\
+ $2:>):>)
+