Fix Codegen fails when trying to create wrapper from ABI compiled by …

[DakshRJain737]

Fixes #1925

What does this PR do?

Codegen fails when trying to create wrapper from ABI compiled by truffle for T-REX 4.0.0+. The root cause is in createMappedParameterTypes() in SolidityFunctionWrapper.java, where the code blindly casts a TypeName to ClassName without checking its actual type first. When the inner type argument is a ParameterizedTypeName (which happens with nested arrays like uint256[][]), the cast fails.

Added an instanceof ClassName guard before the cast, and extracted the type argument into a variable to avoid redundant calls:

TypeName firstTypeArg = typeNames.get(0);
if (firstTypeArg instanceof ClassName && structClassNameMap.values().stream()...)

If the type argument is not a ClassName (i.e. it's a nested array), it correctly falls through to the existing else block which handles ParameterizedTypeName properly.

Where should the reviewer start?

The reviewer must just look into the codegen/src/main/java/org/web3j/codegen/SolidityFunctionWrapper.java file.

Why is it needed?

Because the code assumed every type inside an array is a simple type (ClassName), but for nested arrays like uint256[][], the inner type is itself another array (ParameterizedTypeName).

Checklist

• I've read the contribution guidelines.
• I've added tests (if applicable).
• I've added a changelog entry if necessary.