rpc: update validateaddress RPCExamples to bech32

also contains the following changes:
- rpc: factor out example bech32 address for RPCExamples
- doc: update developer notes wrt RPCExamples addresses
 (mention the EXAMPLE_ADDRESS constant as an example for an invalid bech32
  address suitable for RPCExamples help documentation)

doc/developer-notes.md

@@ -1089,7 +1089,8 @@ A few guidelines for introducing and reviewing new RPC interfaces:
     new RPC is replacing a deprecated RPC, to avoid both RPCs confusingly
     showing up in the command list.
 
-- Use *invalid* bech32 addresses for `RPCExamples` help documentation.
+- Use *invalid* bech32 addresses (e.g. the constant `EXAMPLE_ADDRESS`) for
+  `RPCExamples` help documentation.
 
   - *Rationale*: Prevent accidental transactions by users and encourage the use
     of bech32 addresses by default.

src/rpc/misc.cpp

@@ -42,8 +42,8 @@ static UniValue validateaddress(const JSONRPCRequest& request)
             "}\n"
                 },
                 RPCExamples{
-                    HelpExampleCli("validateaddress", "\"1PSSGeFHDnKNxiEyFrD1wcEaHr9hrQDDWc\"")
-            + HelpExampleRpc("validateaddress", "\"1PSSGeFHDnKNxiEyFrD1wcEaHr9hrQDDWc\"")
+                    HelpExampleCli("validateaddress", EXAMPLE_ADDRESS) +
+                    HelpExampleRpc("validateaddress", EXAMPLE_ADDRESS)
                 },
             }.Check(request);
 

src/rpc/util.cpp

@@ -14,6 +14,7 @@
 #include <tuple>
 
 const std::string UNIX_EPOCH_TIME = "UNIX epoch time";
+const std::string EXAMPLE_ADDRESS = "\"bc1q09vm5lfy0j5reeulh4x5752q25uqqvz34hufdl\"";
 
 void RPCTypeCheck(const UniValue& params,
                   const std::list<UniValueType>& typesExpected,

src/rpc/util.h

@@ -28,6 +28,12 @@
  */
 extern const std::string UNIX_EPOCH_TIME;
 
+/**
+ * Example bech32 address used in multiple RPCExamples. The address is intentionally
+ * invalid to prevent accidental transactions by users.
+ */
+extern const std::string EXAMPLE_ADDRESS;
+
 class FillableSigningProvider;
 class CPubKey;
 class CScript;

src/wallet/rpcwallet.cpp

@@ -3737,8 +3737,6 @@ UniValue getaddressinfo(const JSONRPCRequest& request)
         return NullUniValue;
     }
 
-    const std::string example_address = "\"bc1q09vm5lfy0j5reeulh4x5752q25uqqvz34hufdl\"";
-
             RPCHelpMan{"getaddressinfo",
                 "\nReturn information about the given bitcoin address.\n"
                 "Some of the information will only be present if the address is in the active wallet.\n",
@@ -3791,8 +3789,8 @@ UniValue getaddressinfo(const JSONRPCRequest& request)
             "}\n"
                 },
                 RPCExamples{
-                    HelpExampleCli("getaddressinfo", example_address) +
-                    HelpExampleRpc("getaddressinfo", example_address)
+                    HelpExampleCli("getaddressinfo", EXAMPLE_ADDRESS) +
+                    HelpExampleRpc("getaddressinfo", EXAMPLE_ADDRESS)
                 },
             }.Check(request);