percent-encode values according the rfc 3986 . the built-in java urlencoder does not encode according to the rfc , so we make the extra replacements . concode_field_sep String awsSecretKey concode_elem_sep String awsAccessKeyId concode_elem_sep String associatetag concode_elem_sep SecretKeySpec secretKeySpec concode_elem_sep String HMAC_SHA256_ALGORITHM concode_elem_sep String REQUEST_METHOD concode_elem_sep String UTF8_CHARSET concode_elem_sep String endpoint concode_elem_sep String REQUEST_URI concode_elem_sep Mac mac concode_field_sep Map<String,String> createParameterMap concode_elem_sep String hmac concode_elem_sep String sign concode_elem_sep String sign concode_elem_sep SignedRequestsHelper getInstance concode_elem_sep String canonicalize concode_elem_sep String timestamp