Additional modifications that weren't included in the merge.

src/integration-test/java/org/web3j/protocol/scenarios/DeployContractIT.java

@@ -53,7 +53,7 @@ public void testContractCreation() throws Exception {
         List<Type> uint = FunctionReturnDecoder.decode(
                 responseValue, function.getOutputParameters());
         assertThat(uint.size(), is(1));
-        assertThat(uint.get(0).getValue(), equalTo(BigInteger.valueOf(13)));
+        assertThat((BigInteger) uint.get(0).getValue(), equalTo(BigInteger.valueOf(13)));
     }
 
     private String sendTransaction() throws Exception {

src/integration-test/java/org/web3j/protocol/scenarios/GreeterContractIT.java

@@ -60,7 +60,7 @@ public void testGreeterContract() throws Exception {
         List<Type> response = FunctionReturnDecoder.decode(
                 responseValue, getFunction.getOutputParameters());
         assertThat(response.size(), is(1));
-        assertThat(response.get(0).getValue(), is(VALUE));
+        assertThat((String) response.get(0).getValue(), is(VALUE));
     }
 
     private String sendCreateContractTransaction() throws Exception {
@@ -104,7 +104,7 @@ private static String getGreeterSolidityBinary() throws Exception {
     Function createGreetFunction() {
         return new Function(
                 "greet",
-                Collections.emptyList(),
-                Collections.singletonList(new TypeReference<Utf8String>() {}));
+                Collections.<Type>emptyList(),
+                Collections.<TypeReference<?>>singletonList(new TypeReference<Utf8String>() {}));
     }
 }

src/integration-test/java/org/web3j/protocol/scenarios/HumanStandardTokenIT.java

@@ -105,7 +105,7 @@ private void confirmBalance(
         List<Type> response = FunctionReturnDecoder.decode(
                 responseValue, function.getOutputParameters());
         assertThat(response.size(), is(1));
-        assertThat(response.get(0), equalTo(new Uint256(expected)));
+        assertThat((Uint256) response.get(0), equalTo(new Uint256(expected)));
     }
 
     private void confirmAllowance(String owner, String spender, String contractAddress,
@@ -117,7 +117,7 @@ private void confirmAllowance(String owner, String spender, String contractAddre
                 responseValue, function.getOutputParameters());
 
         assertThat(response.size(), is(function.getOutputParameters().size()));
-        assertThat(response.get(0), equalTo(new Uint256(expected)));
+        assertThat((Uint256) response.get(0), equalTo(new Uint256(expected)));
     }
 
     private String createContract(
@@ -301,43 +301,43 @@ private String callSmartContractFunction(
     private Function totalSupply() {
         return new Function(
                 "totalSupply",
-                Collections.emptyList(),
-                Collections.singletonList(new TypeReference<Uint256>() {}));
+                Collections.<Type>emptyList(),
+                Collections.<TypeReference<?>>singletonList(new TypeReference<Uint256>() {}));
     }
 
     private Function balanceOf(String owner) {
         return new Function(
                 "balanceOf",
-                Collections.singletonList(new Address(owner)),
-                Collections.singletonList(new TypeReference<Uint256>() {}));
+                Collections.<Type>singletonList(new Address(owner)),
+                Collections.<TypeReference<?>>singletonList(new TypeReference<Uint256>() {}));
     }
 
     private Function transfer(String to, BigInteger value) {
         return new Function(
                 "transfer",
-                Arrays.asList(new Address(to), new Uint256(value)),
-                Collections.singletonList(new TypeReference<Bool>() {}));
+                Arrays.<Type>asList(new Address(to), new Uint256(value)),
+                Collections.<TypeReference<?>>singletonList(new TypeReference<Bool>() {}));
     }
 
     private Function allowance(String owner, String spender) {
         return new Function(
                 "allowance",
-                Arrays.asList(new Address(owner), new Address(spender)),
-                Collections.singletonList(new TypeReference<Uint256>() {}));
+                Arrays.<Type>asList(new Address(owner), new Address(spender)),
+                Collections.<TypeReference<?>>singletonList(new TypeReference<Uint256>() {}));
     }
 
     private Function approve(String spender, BigInteger value) {
         return new Function(
                 "approve",
-                Arrays.asList(new Address(spender), new Uint256(value)),
-                Collections.singletonList(new TypeReference<Bool>() {}));
+                Arrays.<Type>asList(new Address(spender), new Uint256(value)),
+                Collections.<TypeReference<?>>singletonList(new TypeReference<Bool>() {}));
     }
 
     private Function transferFrom(String from, String to, BigInteger value) {
         return new Function(
                 "transferFrom",
-                Arrays.asList(new Address(from), new Address(to), new Uint256(value)),
-                Collections.singletonList(new TypeReference<Bool>() {}));
+                Arrays.<Type>asList(new Address(from), new Address(to), new Uint256(value)),
+                Collections.<TypeReference<?>>singletonList(new TypeReference<Bool>() {}));
     }
 
     private Event transferEvent() {

src/main/java/org/web3j/abi/Contract.java

@@ -69,9 +69,9 @@ public T call() throws Exception {
         });
     }
 
-    protected <Type> Future<List<T>> executeCallMultipleValueReturnAsync(
+    protected Future<List<Type>> executeCallMultipleValueReturnAsync(
             final Function function) {
-        return Async.run(new Callable<List<T>>() {
+        return Async.run(new Callable<List<Type>>() {
             @Override
             public List<Type> call() throws Exception {
                 return executeCallMultipleValueReturn(function);

src/main/java/org/web3j/abi/Utils.java

@@ -2,7 +2,6 @@
 
 import java.util.ArrayList;
 import java.util.List;
-import java.util.stream.Collectors;
 
 import sun.reflect.generics.reflectiveObjects.ParameterizedTypeImpl;
 
@@ -83,10 +82,12 @@ static <T extends Type> Class<T> getParameterizedTypeFromArray(
 
     @SuppressWarnings("unchecked")
     public static List<TypeReference<Type>> convert(List<TypeReference<?>> input) {
-        List<TypeReference<Type>> result = new ArrayList<>(input.size());
-        result.addAll(input.stream()
-                .map(typeReference -> (TypeReference<Type>) typeReference)
-                .collect(Collectors.toList()));
+        List<TypeReference<Type>> result = new ArrayList<TypeReference<Type>>(input.size());
+
+        for (TypeReference<?> typeReference:input) {
+            result.add((TypeReference<Type>) typeReference);
+        }
+
         return result;
     }
 }

src/main/java/org/web3j/protocol/infura/CertificateManager.java

@@ -100,7 +100,7 @@ private static boolean isTrustedEndPoint(SSLSocket socket) throws IOException {
         }
     }
 
-    private static void deleteFileOnShutdown(File file) {
+    private static void deleteFileOnShutdown(final File file) {
         Runtime.getRuntime().addShutdownHook(new Thread() {
             public void run() {
                 try {

src/main/java/org/web3j/protocol/infura/InfuraHttpService.java

@@ -6,7 +6,6 @@
 import java.security.*;
 import java.security.cert.CertificateException;
 import java.util.List;
-import java.util.Optional;
 
 import org.apache.http.Header;
 import org.apache.http.impl.client.CloseableHttpClient;
@@ -26,7 +25,7 @@ public class InfuraHttpService extends HttpService {
 
     private static final char[] TEMP_KEY_STORE_PASSWORD = "web3j runtime cert store".toCharArray();
 
-    private final Optional<Header> clientVersionHeader;
+    private final Header clientVersionHeader;
 
     public InfuraHttpService(String url, String clientVersion, boolean required) {
         super(url);
@@ -44,21 +43,21 @@ public InfuraHttpService(String url) {
 
     @Override
     protected void addHeaders(List<Header> headers) {
-        if (clientVersionHeader.isPresent()) {
-            headers.add(clientVersionHeader.get());
+        if (clientVersionHeader != null) {
+            headers.add(clientVersionHeader);
         }
     }
 
-    static Optional<Header> buildHeader(String clientVersion, boolean required) {
+    static Header buildHeader(String clientVersion, boolean required) {
         if (clientVersion == null || clientVersion.equals("")) {
-            return Optional.empty();
+            return null;
         }
 
         if (required) {
-            return Optional.of(new BasicHeader(INFURA_ETHEREUM_PREFERRED_CLIENT, clientVersion));
+            return new BasicHeader(INFURA_ETHEREUM_PREFERRED_CLIENT, clientVersion);
         } else {
-            return Optional.of(new BasicHeader(
-                    INFURA_ETHEREUM_PREFERRED_CLIENT, clientVersion + "; required=false"));
+            return new BasicHeader(
+                    INFURA_ETHEREUM_PREFERRED_CLIENT, clientVersion + "; required=false");
         }
     }
 

src/test/java/org/web3j/abi/FunctionReturnDecoderTest.java

@@ -49,7 +49,7 @@ public void testSimpleFunctionStringResultDecode() {
                         "6f6e65206d6f72652074696d6500000000000000000000000000000000000000",
                 function.getOutputParameters());
 
-        assertThat(utf8Strings.get(0).getValue(), is("one more time"));
+        assertThat((String) utf8Strings.get(0).getValue(), is("one more time"));
     }
 
     @Test
@@ -64,15 +64,16 @@ public void testFunctionEmptyStringResultDecode() {
                         "0000000000000000000000000000000000000000000000000000000000000000",
                 function.getOutputParameters());
 
-        assertThat(utf8Strings.get(0).getValue(), is(""));
+        assertThat((String) utf8Strings.get(0).getValue(), is(""));
     }
 
     @Test
     public void testMultipleResultFunctionDecode() {
         Function function = new Function(
                 "test",
                 Collections.<Type>emptyList(),
-                Arrays.asList(new TypeReference<Uint>() { }, new TypeReference<Uint>() { })
+                Arrays.<TypeReference<?>>asList(
+                        new TypeReference<Uint>() { }, new TypeReference<Uint>() { })
         );
 
         assertThat(FunctionReturnDecoder.decode(

src/test/java/org/web3j/protocol/infura/InfuraHttpServiceTest.java

@@ -5,23 +5,23 @@
 import org.junit.Test;
 
 import static org.hamcrest.core.Is.is;
-import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertThat;
 import static org.web3j.protocol.infura.InfuraHttpService.buildHeader;
 
 public class InfuraHttpServiceTest {
 
     @Test
     public void testBuildHeader() {
-        assertFalse(buildHeader("", false).isPresent());
-        assertFalse(buildHeader(null, false).isPresent());
+        assertNull(buildHeader("", false));
+        assertNull(buildHeader(null, false));
 
-        assertThat(buildHeader("geth 1.4.19", true).get().toString(),
+        assertThat(buildHeader("geth 1.4.19", true).toString(),
                 is(new BasicHeader(
                         "Infura-Ethereum-Preferred-Client",
                         "geth 1.4.19").toString()));
 
-        assertThat(buildHeader("geth 1.4.19", false).get().toString(),
+        assertThat(buildHeader("geth 1.4.19", false).toString(),
                 is(new BasicHeader(
                         "Infura-Ethereum-Preferred-Client",
                         "geth 1.4.19; required=false").toString()));