@Entity( name = "EntityA" )
	public static class EntityA {
		@Id
		private Long id;

		private Integer amount;

		@ManyToOne
		@JoinColumn( name = "secondary_id" )
		private EntityB secondary;

		public EntityA() {
		}

		public EntityA(Long id, Integer amount, EntityB secondary) {
			this.id = id;
			this.amount = amount;
			this.secondary = secondary;
		}

		public Long getId() {
			return id;
		}

		public Integer getAmount() {
			return amount;
		}

		public EntityB getSecondary() {
			return secondary;
		}

	}

	@Entity( name = "EntityB" )
	public static class EntityB {
		@Id
		@Column( name = "id_col" )
		private Long id;

		private String name;

		// We need a 'json' column to reproduce the bug; 'jsonb' would work just fine.
		@JdbcType(PostgreSQLJsonPGObjectJsonType.class)
		// For some reason PostgreSQLJsonPGObjectJsonType
		// will still lead to the column being defined as jsonb...
		@Column(columnDefinition = "json")
		private Map<String, Object> metadata;

		public EntityB() {
		}

		public EntityB(Long id, String name, Map<String, Object> metadata) {
			this.id = id;
			this.name = name;
			this.metadata = metadata;
		}

		public Long getId() {
			return id;
		}

		public String getName() {
			return name;
		}

		public Map<String, Object> getMetadata() {
			return metadata;
		}
	}

select b.name from EntityB b group by b

org.hibernate.exception.SQLGrammarException: JDBC exception executing SQL [select e1_0.name from EntityB e1_0 group by e1_0.id_col,e1_0.metadata,e1_0.name] [ERROR: could not identify an equality operator for type json
  Position: 57] [n/a]
	at app//org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:89)
	at app//org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:56)
	at app//org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:108)
	at app//org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:94)
	at app//org.hibernate.sql.results.jdbc.internal.DeferredResultSetAccess.executeQuery(DeferredResultSetAccess.java:257)
	at app//org.hibernate.sql.results.jdbc.internal.DeferredResultSetAccess.getResultSet(DeferredResultSetAccess.java:163)
	at app//org.hibernate.sql.results.jdbc.internal.JdbcValuesResultSetImpl.advanceNext(JdbcValuesResultSetImpl.java:254)
	at app//org.hibernate.sql.results.jdbc.internal.JdbcValuesResultSetImpl.processNext(JdbcValuesResultSetImpl.java:134)
	at app//org.hibernate.sql.results.jdbc.internal.AbstractJdbcValues.next(AbstractJdbcValues.java:19)
	at app//org.hibernate.sql.results.internal.RowProcessingStateStandardImpl.next(RowProcessingStateStandardImpl.java:66)
	at app//org.hibernate.sql.results.spi.ListResultsConsumer.consume(ListResultsConsumer.java:198)
	at app//org.hibernate.sql.results.spi.ListResultsConsumer.consume(ListResultsConsumer.java:33)
	at app//org.hibernate.sql.exec.internal.JdbcSelectExecutorStandardImpl.doExecuteQuery(JdbcSelectExecutorStandardImpl.java:361)
	at app//org.hibernate.sql.exec.internal.JdbcSelectExecutorStandardImpl.executeQuery(JdbcSelectExecutorStandardImpl.java:168)
	at app//org.hibernate.sql.exec.internal.JdbcSelectExecutorStandardImpl.list(JdbcSelectExecutorStandardImpl.java:93)
	at app//org.hibernate.sql.exec.spi.JdbcSelectExecutor.list(JdbcSelectExecutor.java:31)
	at app//org.hibernate.query.sqm.internal.ConcreteSqmSelectQueryPlan.lambda$new$0(ConcreteSqmSelectQueryPlan.java:115)
	at app//org.hibernate.query.sqm.internal.ConcreteSqmSelectQueryPlan.withCacheableSqmInterpretation(ConcreteSqmSelectQueryPlan.java:311)
	at app//org.hibernate.query.sqm.internal.ConcreteSqmSelectQueryPlan.performList(ConcreteSqmSelectQueryPlan.java:252)
	at app//org.hibernate.query.sqm.internal.QuerySqmImpl.doList(QuerySqmImpl.java:518)
	at app//org.hibernate.query.spi.AbstractSelectionQuery.list(AbstractSelectionQuery.java:430)
	at app//org.hibernate.query.spi.AbstractSelectionQuery.getSingleResult(AbstractSelectionQuery.java:536)
	at app//org.hibernate.orm.test.query.EntityValuedPathsGroupByWithNoEqualityOperatorTest.lambda$testRootGroupBy$2(EntityValuedPathsGroupByWithNoEqualityOperatorTest.java:67)
	at app//org.hibernate.testing.orm.transaction.TransactionUtil.wrapInTransaction(TransactionUtil.java:49)
	at app//org.hibernate.testing.orm.transaction.TransactionUtil.inTransaction(TransactionUtil.java:24)
	at app//org.hibernate.testing.orm.junit.SessionFactoryExtension$SessionFactoryScopeImpl.inTransaction(SessionFactoryExtension.java:375)
	at app//org.hibernate.testing.orm.junit.SessionFactoryExtension$SessionFactoryScopeImpl.inTransaction(SessionFactoryExtension.java:352)
	at app//org.hibernate.orm.test.query.EntityValuedPathsGroupByWithNoEqualityOperatorTest.testRootGroupBy(EntityValuedPathsGroupByWithNoEqualityOperatorTest.java:64)
	[...]
Caused by: org.postgresql.util.PSQLException: ERROR: could not identify an equality operator for type json
  Position: 57
	at app//org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2713)
	at app//org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:2401)
	at app//org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:368)
	at app//org.postgresql.jdbc.PgStatement.executeInternal(PgStatement.java:498)
	at app//org.postgresql.jdbc.PgStatement.execute(PgStatement.java:415)
	at app//org.postgresql.jdbc.PgPreparedStatement.executeWithFlags(PgPreparedStatement.java:190)
	at app//org.postgresql.jdbc.PgPreparedStatement.executeQuery(PgPreparedStatement.java:134)
	at app//org.hibernate.sql.results.jdbc.internal.DeferredResultSetAccess.executeQuery(DeferredResultSetAccess.java:239)
	... 106 more