chore: Various code cleanup

src/main/java/com/danubetech/verifiablecredentials/CredentialSubject.java

@@ -5,6 +5,7 @@
 import com.apicatalog.jsonld.loader.DocumentLoader;
 import com.danubetech.verifiablecredentials.jsonld.VerifiableCredentialContexts;
 import com.danubetech.verifiablecredentials.jsonld.VerifiableCredentialKeywords;
+import com.danubetech.verifiablecredentials.proof.BlockchainHashProof2020;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import foundation.identity.jsonld.JsonLDKeywords;
 import foundation.identity.jsonld.JsonLDObject;
@@ -14,7 +15,6 @@
 import java.net.URI;
 import java.util.LinkedHashMap;
 import java.util.Map;
-import java.util.stream.Collectors;
 
 public class CredentialSubject extends JsonLDObject {
 
@@ -62,7 +62,7 @@ public B claims(Map<String, Object> claims) {
 	}
 
 	public static Builder<? extends Builder<?>> builder() {
-		return new Builder(new CredentialSubject());
+		return new Builder<? extends BlockchainHashProof2020.Builder<?>>(new CredentialSubject());
 	}
 
 	public static CredentialSubject fromJsonObject(Map<String, Object> jsonObject) {

src/main/java/com/danubetech/verifiablecredentials/VerifiableCredential.java

@@ -4,6 +4,7 @@
 import com.danubetech.verifiablecredentials.credentialstatus.CredentialStatus;
 import com.danubetech.verifiablecredentials.jsonld.VerifiableCredentialContexts;
 import com.danubetech.verifiablecredentials.jsonld.VerifiableCredentialKeywords;
+import com.danubetech.verifiablecredentials.proof.BlockchainHashProof2020;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import foundation.identity.jsonld.JsonLDObject;
 import foundation.identity.jsonld.JsonLDUtils;
@@ -99,7 +100,7 @@ public B ldProof(LdProof ldProof) {
 	}
 
 	public static Builder<? extends Builder<?>> builder() {
-		return new Builder(new VerifiableCredential());
+		return new Builder<? extends BlockchainHashProof2020.Builder<?>>(new VerifiableCredential());
 	}
 
 	public static VerifiableCredential fromJsonObject(Map<String, Object> jsonObject) {

src/main/java/com/danubetech/verifiablecredentials/VerifiablePresentation.java

@@ -3,6 +3,7 @@
 import com.apicatalog.jsonld.loader.DocumentLoader;
 import com.danubetech.verifiablecredentials.jsonld.VerifiableCredentialContexts;
 import com.danubetech.verifiablecredentials.jsonld.VerifiableCredentialKeywords;
+import com.danubetech.verifiablecredentials.proof.BlockchainHashProof2020;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import foundation.identity.jsonld.JsonLDObject;
 import foundation.identity.jsonld.JsonLDUtils;
@@ -77,7 +78,7 @@ public B ldProof(LdProof ldProof) {
 	}
 
 	public static Builder<? extends Builder<?>> builder() {
-		return new Builder(new VerifiablePresentation());
+		return new Builder<? extends BlockchainHashProof2020.Builder<?>>(new VerifiablePresentation());
 	}
 
 	public static VerifiablePresentation fromJsonObject(Map<String, Object> jsonObject) {
@@ -148,7 +149,7 @@ public URI getHolder() {
 
 	public VerifiableCredential getVerifiableCredential() {
 		Object verifiableCredentialObject = this.getJsonObject().get(VerifiableCredentialKeywords.JSONLD_TERM_VERIFIABLECREDENTIAL);
-		if ((verifiableCredentialObject instanceof List && ! ((List) verifiableCredentialObject).isEmpty() && ((List) verifiableCredentialObject).get(0) instanceof Map)) {
+		if ((verifiableCredentialObject instanceof List<?> && ! ((List<?>) verifiableCredentialObject).isEmpty() && ((List<?>) verifiableCredentialObject).get(0) instanceof Map)) {
 			return VerifiableCredential.getFromJsonLDObject(this);
 		} else if (verifiableCredentialObject instanceof Map) {
 			return VerifiableCredential.getFromJsonLDObject(this);
@@ -158,8 +159,8 @@ public VerifiableCredential getVerifiableCredential() {
 
 	public String getJwtVerifiableCredentialString() {
 		Object verifiableCredentialObject = this.getJsonObject().get(VerifiableCredentialKeywords.JSONLD_TERM_VERIFIABLECREDENTIAL);
-		if (verifiableCredentialObject instanceof List && ! ((List) verifiableCredentialObject).isEmpty() && ((List) verifiableCredentialObject).get(0) instanceof String) {
-			return (String) ((List) verifiableCredentialObject).get(0);
+		if (verifiableCredentialObject instanceof List<?> && ! ((List<?>) verifiableCredentialObject).isEmpty() && ((List<?>) verifiableCredentialObject).get(0) instanceof String) {
+			return (String) ((List<?>) verifiableCredentialObject).get(0);
 		} else if (verifiableCredentialObject instanceof String) {
 			return (String) verifiableCredentialObject;
 		}

src/main/java/com/danubetech/verifiablecredentials/credentialstatus/CredentialStatus.java

@@ -1,12 +1,11 @@
 package com.danubetech.verifiablecredentials.credentialstatus;
 
 import com.apicatalog.jsonld.loader.DocumentLoader;
-import com.danubetech.verifiablecredentials.CredentialSubject;
 import com.danubetech.verifiablecredentials.jsonld.VerifiableCredentialContexts;
 import com.danubetech.verifiablecredentials.jsonld.VerifiableCredentialKeywords;
+import com.danubetech.verifiablecredentials.proof.BlockchainHashProof2020;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import foundation.identity.jsonld.JsonLDObject;
-import foundation.identity.jsonld.JsonLDUtils;
 
 import java.io.Reader;
 import java.net.URI;
@@ -48,7 +47,7 @@ public CredentialStatus build() {
 	}
 
 	public static Builder<? extends Builder<?>> builder() {
-		return new Builder(new CredentialStatus());
+		return new Builder<? extends BlockchainHashProof2020.Builder<?>>(new CredentialStatus());
 	}
 
 	public static CredentialStatus fromJsonObject(Map<String, Object> jsonObject) {

src/main/java/com/danubetech/verifiablecredentials/credentialstatus/RevocationList2020Status.java

@@ -1,9 +1,9 @@
 package com.danubetech.verifiablecredentials.credentialstatus;
 
 import com.apicatalog.jsonld.loader.DocumentLoader;
-import com.danubetech.verifiablecredentials.CredentialSubject;
 import com.danubetech.verifiablecredentials.jsonld.VerifiableCredentialContexts;
 import com.danubetech.verifiablecredentials.jsonld.VerifiableCredentialKeywords;
+import com.danubetech.verifiablecredentials.proof.BlockchainHashProof2020;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import foundation.identity.jsonld.JsonLDObject;
 import foundation.identity.jsonld.JsonLDUtils;
@@ -66,7 +66,7 @@ public B revocationListCredential(URI revocationListCredential) {
 	}
 
 	public static Builder<? extends Builder<?>> builder() {
-		return new Builder(new RevocationList2020Status());
+		return new Builder<? extends BlockchainHashProof2020.Builder<?>>(new RevocationList2020Status());
 	}
 
 	public static RevocationList2020Status fromJsonObject(Map<String, Object> jsonObject) {

src/main/java/com/danubetech/verifiablecredentials/credentialstatus/RevocationQuery2020Status.java

@@ -7,7 +7,6 @@
 import com.fasterxml.jackson.annotation.JsonCreator;
 import foundation.identity.jsonld.JsonLDObject;
 import foundation.identity.jsonld.JsonLDUtils;
-import info.weboftrust.ldsignatures.LdProof;
 
 import java.io.Reader;
 import java.net.URI;
@@ -67,7 +66,7 @@ public B revocationService(String revocationService) {
 	}
 
 	public static Builder<? extends Builder<?>> builder() {
-		return new Builder(new RevocationQuery2020Status());
+		return new Builder<? extends BlockchainHashProof2020.Builder<?>>(new RevocationQuery2020Status());
 	}
 
 	public static RevocationQuery2020Status fromJsonObject(Map<String, Object> jsonObject) {

src/main/java/com/danubetech/verifiablecredentials/credentialstatus/StatusList2021Entry.java

@@ -3,6 +3,7 @@
 import com.apicatalog.jsonld.loader.DocumentLoader;
 import com.danubetech.verifiablecredentials.jsonld.VerifiableCredentialContexts;
 import com.danubetech.verifiablecredentials.jsonld.VerifiableCredentialKeywords;
+import com.danubetech.verifiablecredentials.proof.BlockchainHashProof2020;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import foundation.identity.jsonld.JsonLDObject;
 import foundation.identity.jsonld.JsonLDUtils;
@@ -73,7 +74,7 @@ public B statusPurpose(String statusPurpose) {
     }
 
     public static StatusList2021Entry.Builder<? extends StatusList2021Entry.Builder<?>> builder() {
-        return new StatusList2021Entry.Builder(new StatusList2021Entry());
+        return new StatusList2021Entry.Builder<? extends BlockchainHashProof2020.Builder<?>>(new StatusList2021Entry());
     }
 
     public static StatusList2021Entry fromJsonObject(Map<String, Object> jsonObject) {

src/main/java/com/danubetech/verifiablecredentials/jsonld/VerifiableCredentialContexts.java

@@ -10,6 +10,7 @@
 import java.net.URI;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Objects;
 
 public class VerifiableCredentialContexts {
 
@@ -34,21 +35,21 @@ public class VerifiableCredentialContexts {
             CONTEXTS.putAll(LDSecurityContexts.CONTEXTS);
 
             CONTEXTS.put(JSONLD_CONTEXT_W3C_2018_CREDENTIALS_V1,
-                    JsonDocument.of(MediaType.JSON_LD, VerifiableCredentialContexts.class.getResourceAsStream("credentials-v1.jsonld")));
+                    JsonDocument.of(MediaType.JSON_LD, Objects.requireNonNull(VerifiableCredentialContexts.class.getResourceAsStream("credentials-v1.jsonld"))));
             CONTEXTS.put(JSONLD_CONTEXT_W3C_2018_CREDENTIALS_V2,
-                    JsonDocument.of(MediaType.JSON_LD, VerifiableCredentialContexts.class.getResourceAsStream("credentials-v2-unstable.jsonld")));
+                    JsonDocument.of(MediaType.JSON_LD, Objects.requireNonNull(VerifiableCredentialContexts.class.getResourceAsStream("credentials-v2-unstable.jsonld"))));
             CONTEXTS.put(JSONLD_CONTEXT_W3C_2018_CREDENTIALS_EXAMPLES_V1,
-                    JsonDocument.of(MediaType.JSON_LD, VerifiableCredentialContexts.class.getResourceAsStream("credentials-examples-v1.jsonld")));
+                    JsonDocument.of(MediaType.JSON_LD, Objects.requireNonNull(VerifiableCredentialContexts.class.getResourceAsStream("credentials-examples-v1.jsonld"))));
             CONTEXTS.put(JSONLD_CONTEXT_W3C_NS_ODRL,
-                    JsonDocument.of(MediaType.JSON_LD, VerifiableCredentialContexts.class.getResourceAsStream("odrl.jsonld")));
+                    JsonDocument.of(MediaType.JSON_LD, Objects.requireNonNull(VerifiableCredentialContexts.class.getResourceAsStream("odrl.jsonld"))));
             CONTEXTS.put(JSONLD_CONTEXT_DANUBETECH_2020_CREDENTIALS_V1,
-                    JsonDocument.of(MediaType.JSON_LD, VerifiableCredentialContexts.class.getResourceAsStream("danubetech-v1.jsonld")));
+                    JsonDocument.of(MediaType.JSON_LD, Objects.requireNonNull(VerifiableCredentialContexts.class.getResourceAsStream("danubetech-v1.jsonld"))));
             CONTEXTS.put(JSONLD_CONTEXT_W3ID_VC_REVOCATION_LIST_2020_V1,
-                    JsonDocument.of(MediaType.JSON_LD, VerifiableCredentialContexts.class.getResourceAsStream("vc-revocation-list-2020-v1.jsonld")));
+                    JsonDocument.of(MediaType.JSON_LD, Objects.requireNonNull(VerifiableCredentialContexts.class.getResourceAsStream("vc-revocation-list-2020-v1.jsonld"))));
             CONTEXTS.put(JSONLD_CONTEXT_W3ID_VC_STATUS_LIST_2021_V1,
-                    JsonDocument.of(MediaType.JSON_LD, VerifiableCredentialContexts.class.getResourceAsStream("vc-status-list-2021-v1.jsonld")));
+                    JsonDocument.of(MediaType.JSON_LD, Objects.requireNonNull(VerifiableCredentialContexts.class.getResourceAsStream("vc-status-list-2021-v1.jsonld"))));
             CONTEXTS.put(JSONLD_CONTEXT_DIF_PRESENTATION_EXCHANGE_SUBMISSIONS_V1,
-                    JsonDocument.of(MediaType.JSON_LD, VerifiableCredentialContexts.class.getResourceAsStream("presentation-exchange-submissions-v1.jsonld")));
+                    JsonDocument.of(MediaType.JSON_LD, Objects.requireNonNull(VerifiableCredentialContexts.class.getResourceAsStream("presentation-exchange-submissions-v1.jsonld"))));
 
             for (Map.Entry<URI, JsonDocument> context : CONTEXTS.entrySet()) {
                 context.getValue().setDocumentUrl(context.getKey());

src/main/java/com/danubetech/verifiablecredentials/jwt/FromJwtConverter.java

@@ -4,6 +4,7 @@
 import com.danubetech.verifiablecredentials.VerifiableCredential;
 import com.danubetech.verifiablecredentials.VerifiablePresentation;
 import com.danubetech.verifiablecredentials.jsonld.VerifiableCredentialKeywords;
+import com.danubetech.verifiablecredentials.proof.BlockchainHashProof2020;
 import com.nimbusds.jwt.JWTClaimsSet;
 import foundation.identity.jsonld.JsonLDUtils;
 
@@ -23,7 +24,7 @@ public static VerifiableCredential fromJwtVerifiableCredential(JwtVerifiableCred
         CredentialSubject payloadCredentialSubject = payloadVerifiableCredential.getCredentialSubject();
         CredentialSubject.removeFromJsonLdObject(payloadVerifiableCredential);
 
-        VerifiableCredential.Builder verifiableCredentialBuilder = VerifiableCredential.builder()
+        VerifiableCredential.Builder<? extends BlockchainHashProof2020.Builder<?>> verifiableCredentialBuilder = VerifiableCredential.builder()
                 .base(payloadVerifiableCredential)
                 .defaultContexts(false)
                 .defaultTypes(false);
@@ -37,7 +38,7 @@ public static VerifiableCredential fromJwtVerifiableCredential(JwtVerifiableCred
 
         if (payloadCredentialSubject != null) {
 
-            CredentialSubject.Builder credentialSubjectBuilder = CredentialSubject.builder()
+            CredentialSubject.Builder<? extends BlockchainHashProof2020.Builder<?>> credentialSubjectBuilder = CredentialSubject.builder()
                     .base(payloadCredentialSubject);
 
             String subject = payload.getSubject();
@@ -74,7 +75,7 @@ public static VerifiablePresentation fromJwtVerifiablePresentation(JwtVerifiable
 
         VerifiablePresentation payloadVerifiablePresentation = VerifiablePresentation.fromJson(jwtVerifiablePresentation.getPayloadObject().toString());
 
-        VerifiablePresentation.Builder verifiablePresentationBuilder = VerifiablePresentation.builder()
+        VerifiablePresentation.Builder<? extends BlockchainHashProof2020.Builder<?>> verifiablePresentationBuilder = VerifiablePresentation.builder()
                 .base(payloadVerifiablePresentation)
                 .defaultContexts(false)
                 .defaultTypes(false);

src/main/java/com/danubetech/verifiablecredentials/jwt/JwtJwtVerifiablePresentation.java

@@ -19,7 +19,7 @@ private JwtJwtVerifiablePresentation(JWTClaimsSet payload, JwtVerifiableCredenti
 	 * Factory methods
 	 */
 
-	public static JwtJwtVerifiablePresentation fromJwtVerifiableCredential(JwtVerifiableCredential jwtVerifiableCredential, String aud) throws  IOException {
+	public static JwtJwtVerifiablePresentation fromJwtVerifiableCredential(JwtVerifiableCredential jwtVerifiableCredential, String aud) throws IOException {
 
 		JwtVerifiableCredential payloadJwtVerifiableCredential = jwtVerifiableCredential;
 		VerifiablePresentation verifiablePresentation = FromJwtConverter.fromJwtVerifiableCredentialToVerifiablePresentation(payloadJwtVerifiableCredential);
@@ -28,7 +28,7 @@ public static JwtJwtVerifiablePresentation fromJwtVerifiableCredential(JwtVerifi
 
 		Date issueTime = new Date();
 
-		payloadBuilder.jwtID("urn:uuid:" + UUID.randomUUID().toString());
+		payloadBuilder.jwtID("urn:uuid:" + UUID.randomUUID());
 		payloadBuilder.issuer(jwtVerifiableCredential.getPayload().getSubject());
 		payloadBuilder.issueTime(issueTime);
 		payloadBuilder.notBeforeTime(issueTime);

src/main/java/com/danubetech/verifiablecredentials/jwt/JwtObject.java

@@ -324,8 +324,6 @@ public boolean verify_P_521_ES512(com.nimbusds.jose.jwk.ECKey publicKey) throws
 
 	private static class EscapedSlashWorkaroundJWSObject extends JWSObject {
 
-		private static final long serialVersionUID = -587898962717783109L;
-
 		public EscapedSlashWorkaroundJWSObject(final JWSHeader jwsHeader, final JWTClaimsSet jwtClaimsSet, boolean canonicalize) {
 			super(jwsHeader, makePayload(jwtClaimsSet, canonicalize));
 		}

src/main/java/com/danubetech/verifiablecredentials/jwt/JwtVerifiableCredential.java

@@ -2,7 +2,6 @@
 
 import com.danubetech.verifiablecredentials.VerifiableCredential;
 import com.nimbusds.jose.JWSObject;
-import com.nimbusds.jose.util.JSONObjectUtils;
 import com.nimbusds.jwt.JWTClaimsSet;
 import com.nimbusds.jwt.SignedJWT;
 

src/main/java/com/danubetech/verifiablecredentials/jwt/JwtVerifiablePresentation.java

@@ -1,6 +1,5 @@
 package com.danubetech.verifiablecredentials.jwt;
 
-import com.danubetech.verifiablecredentials.VerifiableCredential;
 import com.danubetech.verifiablecredentials.VerifiablePresentation;
 import com.nimbusds.jose.JWSObject;
 import com.nimbusds.jwt.JWTClaimsSet;

src/main/java/com/danubetech/verifiablecredentials/proof/BlockchainHashProof2020.java

@@ -1,7 +1,6 @@
 package com.danubetech.verifiablecredentials.proof;
 
 import com.apicatalog.jsonld.loader.DocumentLoader;
-import com.danubetech.verifiablecredentials.CredentialSubject;
 import com.danubetech.verifiablecredentials.jsonld.VerifiableCredentialContexts;
 import com.danubetech.verifiablecredentials.jsonld.VerifiableCredentialKeywords;
 import com.fasterxml.jackson.annotation.JsonCreator;
@@ -50,7 +49,7 @@ public BlockchainHashProof2020 build() {
 	}
 
 	public static Builder<? extends Builder<?>> builder() {
-		return new Builder(new BlockchainHashProof2020());
+		return new Builder<? extends Builder<?>>(new BlockchainHashProof2020());
 	}
 
 	public static BlockchainHashProof2020 fromJsonObject(Map<String, Object> jsonObject) {