AWS S3 URL getting encoded when downloading image file

Question

Need help with the following issue.

The parameter in Aws S3 image url getting encoded when trying to download via wso2 process.

for example Signature sent in parameter along with image url is "RmHyI5zRW5nxwWvitbWMsa%2FEwjA%3D"

However when trying to send the request from wso2 call mediator its rejected by aws server with following message where certain characters in signature have changed "RmHyI5zRW5nxwWvitbWMsa/EwjA="

The characters such as %2F changed as '/', %2B as '+' and %3D as '=' and as result getting signature mismatch error

<?xml version='1.0' encoding='utf-8'?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
    <soapenv:Body>
        <Error>
            <Code>SignatureDoesNotMatch</Code>
            <Message>The request signature we calculated does not match the signature you provided. Check your key and signing method.</Message>
            <AWSAccessKeyId>ASIA4OAOFXPAHYQCKZGD</AWSAccessKeyId>
            <StringToSign>GET

application/json

x-amz-security-token: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
/smile-results-prod/production/000000/353/353-0000010928-hmwgs7m5xvquv196pv48uly3rpobfp/SID_Preview_Full.jpg</StringToSign>
            <SignatureProvided>RmHyI5zRW5nxwWvitbWMsa/EwjA=</SignatureProvided>
            <StringToSignBytes>47 45 54 0a 0a 61 70 70 6c 69 63 61 74 69 6f 6e 2f 6a 73 6f 6e 0a 31 36 39 33 38 31 35 30 38 32 0a 78 2d 61 6d 7a 2d 73 65 63 75 72 69 74 79 2d 74 6f 6b 65 6e 3a 49 51 6f 4a 62 33 4a 70 5a 32 6c 75 58 32 56 6a 45 47 63 61 43 58 56 7a 4c 58 64 6c 63 33 51 74 4d 69 4a 47 4d 45 51 43 49 45 72 62 46 36 2b 33 51 6a 31 65 3 8 6d 77 67 73 37 6d 35 78 76 71 75 76 31 39 36 70 76 34 38 75 6c 79 33 72 70 6f 62 66 70 2f 53 49 44 5f 50 72 65 76 69 65 77 5f 46 75 6c 6c 2e 6a 70 67</StringToSignBytes>
            <RequestId>SG78VW8C3M74MB6D</RequestId>
            <HostId>EhqRjZNgna9/eDzMryNIiYYbN5mw14oLgmXEhsx28yMvVrBShweObyHxku810k8ecobkai+Twjg=</HostId>
        </Error>
    </soapenv:Body>
</soapenv:Envelope>
**your text**

 <resource methods="POST" uri-template="/test">
        <inSequence>
            <property expression="$body//image_url" name="uri.var.selfie_image" scope="default" type="STRING"/>
              <call>
                <endpoint>
                    <http method="get" uri-template="{uri.var.selfie_image}">
                        <suspendOnFailure>
                            <initialDuration>-1</initialDuration>
                            <progressionFactor>-1</progressionFactor>
                            <maximumDuration>0</maximumDuration>
                        </suspendOnFailure>
                        <markForSuspension>
                            <retriesBeforeSuspension>0</retriesBeforeSuspension>
                        </markForSuspension>
                    </http>
                </endpoint>
            </call>
            <respond/>
        </inSequence>
        <outSequence/>
        <faultSequence/>
    </resource>