feat: intent contracts for icon

contracts/javascore/Intent_Contracts/.gitattributes

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+#
+# https://help.github.com/articles/dealing-with-line-endings/
+#
+# Linux start script should use lf
+/gradlew        text eol=lf
+
+# These are Windows script files and should use crlf
+*.bat           text eol=crlf
+

contracts/javascore/Intent_Contracts/.gitignore

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+# Ignore Gradle project-specific cache directory
+.gradle
+
+# Ignore Gradle build output directory
+build

contracts/javascore/Intent_Contracts/app/build.gradle

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+dependencies {
+        compileOnly 'foundation.icon:javaee-api:0.9.6'
+        implementation 'com.github.sink772:javaee-tokens:0.6.4'
+    	testImplementation 'foundation.icon:javaee-unittest:0.10.0'
+    	testImplementation 'org.mockito:mockito-core:4.8.0'
+    	testImplementation 'org.junit.jupiter:junit-jupiter-api:5.9.0'
+    	testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.9.0'
+}
+
+optimizedJar {
+     mainClassName = 'network.icon.intent.Intent'
+     archivesBaseName = "intent" + 1 + ".jar"
+	from {
+    	    configurations.runtimeClasspath.collect {it.isDirectory() ? it : zipTree(it) }
+	}
+
+}
+
+deployJar {
+    endpoints {
+        local {
+            uri = 'http://localhost:9080/api/v3'
+            nid = 0x3
+        }
+    }
+
+    keystore = rootProject.hasProperty('keystoreName') ? "$keystoreName" : ''
+    password = rootProject.hasProperty('keystorePass') ? "$keystorePass" : ''
+}
+
+repositories {
+    mavenCentral() 
+}
+
+
+test {
+     useJUnitPlatform()
+}
+
+

contracts/javascore/Intent_Contracts/app/src/main/java/network/icon/intent/GeneralizedConnection.java

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+package network.icon.intent;
+
+import java.math.BigInteger;
+
+import network.icon.intent.constants.Constant;
+import score.Address;
+import score.BranchDB;
+import score.Context;
+import score.DictDB;
+import score.VarDB;
+import score.annotation.EventLog;
+import score.annotation.External;
+
+public class GeneralizedConnection {
+    private final BranchDB<String, DictDB<BigInteger, Boolean>> receipts = Context.newBranchDB(Constant.RECEIPTS,
+            Boolean.class);
+    protected final VarDB<Address> relayAddress = Context.newVarDB(Constant.RELAY_ADDRESS, Address.class);
+    private final VarDB<BigInteger> connSn = Context.newVarDB(Constant.CONN_SN, BigInteger.class);
+
+    @EventLog(indexed = 3)
+    public void Message(String targetNetwork, BigInteger sn, byte[] _msg) {
+    }
+
+    protected void _sendMessage(
+            String to,
+            byte[] _msg) {
+        connSn.set(connSn.getOrDefault(BigInteger.ZERO).add(BigInteger.ONE));
+        Message(to, connSn.get(), _msg);
+    }
+
+    protected void _recvMessage(String srcNetwork, BigInteger _connSn) {
+        onlyRelay();
+        Context.require(receipts.at(srcNetwork).getOrDefault(_connSn, false).equals(false), "Duplicate Message");
+        receipts.at(srcNetwork).set(_connSn, true);
+    }
+
+    @External
+    public void setAdmin(Address _address) {
+        onlyRelay();
+        relayAddress.set(_address);
+    }
+
+    @External
+    public boolean getReceipt(
+            String srcNetwork,
+            BigInteger _connSn) {
+        return receipts.at(srcNetwork).getOrDefault(_connSn, false);
+    }
+
+    @External
+    public Address admin() {
+        return relayAddress.get();
+    }
+
+    public BigInteger getConnSn() {
+        return connSn.getOrDefault(BigInteger.ZERO);
+    }
+
+    void onlyRelay() {
+        Context.require(Context.getCaller().equals(relayAddress.get()), "OnlyRelayer");
+    }
+
+}