This commit enables struct generation for contracts on java.
It will generate for the TUPLE contract the following:

// TupleP is an auto generated low-level Java binding around an user-defined struct.
	public class TupleP {
		public BigInt x;
		public BigInt y;
	}

	// TupleQ is an auto generated low-level Java binding around an user-defined struct.
	public class TupleQ {
		public BigInt x;
		public BigInt y;
	}

	// TupleS is an auto generated low-level Java binding around an user-defined struct.
	public class TupleS {
		public BigInt a;
		public BigInts b;
		public TupleT[] c;
	}

	// TupleT is an auto generated low-level Java binding around an user-defined struct.
	public class TupleT {
		public BigInt x;
		public BigInt y;
	}

	// Func1Results is the output of a call to func1.
	public class Func1Results {
		public TupleS Return0;
		public TupleT[][] Return1;
		public TupleT[][] Return2;
		public TupleS[] Return3;
		public BigInts Return4;
	}