Issue:
Bug: [REFACTOR]: [Nexi nets] Remove Default Case Handling



### :memo: Feature Description

- We utilize match statements to make pivotal decisions, such as generating requests based on the payment method type and managing responses received from the connector. 
- These conditions generally go hand in hand with enum variants. 
- Default case is used because a match statement needs to be exhaustive i.e. every variant needs to be covered. 
- So, if all the explicit cases are handled then default is used to handle the rest.
- Each connector have these match statements but many of them don’t provide reference to each variant in their default case, rather a `_` is put to handle all the other cases. 
- This approach carries a risk because developers may inadvertently overlook the need for explicit handling of the new cases.

### :hammer: Possible Implementation

- Instead of relying on a default match case `_`, developers should handle each and every variant explicitly. 
- By doing so, if there are any changes in the future, they can readily assess the impact of their modifications simply by compiling the code.
- You can check this PR for further reference https://github.com/juspay/hyperswitch/pull/1955

:bookmark: Note: All the changes needed should be contained within `hyperswitch/crates/router/src/connector/`


### :package: Have you spent some time checking if this feature request has been raised before?

- [X] I checked and didn't find a similar issue

### :package: Have you read the Contributing Guidelines?

- [X] I have read the [Contributing Guidelines](https://github.com/juspay/hyperswitch/blob/main/docs/CONTRIBUTING.md)

### :sparkles: Are you willing to submit a PR?


Pull request description:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [ ] Enhancement
- [x] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- https://github.com/juspay/hyperswitch/issues/2275  -->


### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

<!--
Provide links to the files with corresponding changes.

Following are the paths where you can find config files:
1. `config`
2. `crates/router/src/configs`
3. `loadtest/config`
-->


## Motivation and Context
<!--
Why is this change required? What problem does it solve?
If it fixes an open issue, please link to the issue here.

If you don't have an issue, we'd recommend starting with one first so the PR
can focus on the implementation (unless it is an obvious bug or documentation fix
that will have little conversation).
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## How did you test it?
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Did you write an integration/unit/API test to verify the code changes?
Or did you test this change manually (provide relevant screenshots)?
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## Checklist
<!-- Put an `x` in the boxes that apply -->

- [x] I formatted the code `cargo +nightly fmt --all`
- [x] I addressed lints thrown by `cargo clippy`
- [x] I reviewed the submitted code
- [ ] I added unit tests for my changes where possible
- [ ] I added a [CHANGELOG](/CHANGELOG.md) entry if applicable


Testing:

Patch:
diff --git a/crates/router/src/connector/nexinets/transformers.rs b/crates/router/src/connector/nexinets/transformers.rs
index 897d8f639d3..2af3ee0a1bb 100644
--- a/crates/router/src/connector/nexinets/transformers.rs
+++ b/crates/router/src/connector/nexinets/transformers.rs
@@ -9,7 +9,7 @@ use url::Url;
 
 use crate::{
     connector::utils::{
-        CardData, PaymentsAuthorizeRequestData, PaymentsCancelRequestData, WalletData,
+        self, CardData, PaymentsAuthorizeRequestData, PaymentsCancelRequestData, WalletData,
     },
     consts,
     core::errors,
@@ -597,12 +597,35 @@ fn get_payment_details_and_product(
             api_models::payments::BankRedirectData::Sofort { .. } => {
                 Ok((None, NexinetsProduct::Sofort))
             }
-            _ => Err(errors::ConnectorError::NotImplemented(
-                "Payment methods".to_string(),
-            ))?,
+            api_models::payments::BankRedirectData::BancontactCard { .. }
+            | api_models::payments::BankRedirectData::Blik { .. }
+            | api_models::payments::BankRedirectData::Bizum { .. }
+            | api_models::payments::BankRedirectData::Interac { .. }
+            | api_models::payments::BankRedirectData::OnlineBankingCzechRepublic { .. }
+            | api_models::payments::BankRedirectData::OnlineBankingFinland { .. }
+            | api_models::payments::BankRedirectData::OnlineBankingPoland { .. }
+            | api_models::payments::BankRedirectData::OnlineBankingSlovakia { .. }
+            | api_models::payments::BankRedirectData::OpenBankingUk { .. }
+            | api_models::payments::BankRedirectData::Przelewy24 { .. }
+            | api_models::payments::BankRedirectData::Trustly { .. }
+            | api_models::payments::BankRedirectData::OnlineBankingFpx { .. }
+            | api_models::payments::BankRedirectData::OnlineBankingThailand { .. } => {
+                Err(errors::ConnectorError::NotImplemented(
+                    utils::get_unimplemented_payment_method_error_message("nexinets"),
+                ))?
+            }
         },
-        _ => Err(errors::ConnectorError::NotImplemented(
-            "Payment methods".to_string(),
+        PaymentMethodData::CardRedirect(_)
+        | PaymentMethodData::PayLater(_)
+        | PaymentMethodData::BankDebit(_)
+        | PaymentMethodData::BankTransfer(_)
+        | PaymentMethodData::Crypto(_)
+        | PaymentMethodData::MandatePayment
+        | PaymentMethodData::Reward
+        | PaymentMethodData::Upi(_)
+        | PaymentMethodData::Voucher(_)
+        | PaymentMethodData::GiftCard(_) => Err(errors::ConnectorError::NotImplemented(
+            utils::get_unimplemented_payment_method_error_message("nexinets"),
         ))?,
     }
 }
@@ -677,9 +700,34 @@ fn get_wallet_details(
             ))),
             NexinetsProduct::Applepay,
         )),
-        _ => Err(errors::ConnectorError::NotImplemented(
-            "Payment methods".to_string(),
-        ))?,
+        api_models::payments::WalletData::AliPayQr(_)
+        | api_models::payments::WalletData::AliPayRedirect(_)
+        | api_models::payments::WalletData::AliPayHkRedirect(_)
+        | api_models::payments::WalletData::MomoRedirect(_)
+        | api_models::payments::WalletData::KakaoPayRedirect(_)
+        | api_models::payments::WalletData::GoPayRedirect(_)
+        | api_models::payments::WalletData::GcashRedirect(_)
+        | api_models::payments::WalletData::ApplePayRedirect(_)
+        | api_models::payments::WalletData::ApplePayThirdPartySdk(_)
+        | api_models::payments::WalletData::DanaRedirect { .. }
+        | api_models::payments::WalletData::GooglePay(_)
+        | api_models::payments::WalletData::GooglePayRedirect(_)
+        | api_models::payments::WalletData::GooglePayThirdPartySdk(_)
+        | api_models::payments::WalletData::MbWayRedirect(_)
+        | api_models::payments::WalletData::MobilePayRedirect(_)
+        | api_models::payments::WalletData::PaypalSdk(_)
+        | api_models::payments::WalletData::SamsungPay(_)
+        | api_models::payments::WalletData::TwintRedirect { .. }
+        | api_models::payments::WalletData::VippsRedirect { .. }
+        | api_models::payments::WalletData::TouchNGoRedirect(_)
+        | api_models::payments::WalletData::WeChatPayRedirect(_)
+        | api_models::payments::WalletData::WeChatPayQr(_)
+        | api_models::payments::WalletData::CashappQr(_)
+        | api_models::payments::WalletData::SwishQr(_) => {
+            Err(errors::ConnectorError::NotImplemented(
+                utils::get_unimplemented_payment_method_error_message("nexinets"),
+            ))?
+        }
     }
 }